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PROCEEDINGS 

of the 
NINTH PACIFIC SCIENCE CONGRESS 

of the 

PACIFIC SCIENCE ASSOCIATION 

Held at ChulaUmgkom University 

Bangkok, Thailand 
November 18th to December 9th, 1957 



Under the auspices 

of 
HIS MAJESTY'S GOVERNMENT OF THAILAND 

and 
THE SCIENCE SOCIETY OF THAILAND 



VOLUME 19 
ZOOL.OGY 



Published by the 
SECRETARIAT, NINTH PACIFIC SCIENCE 

DEPARTMENT OF SCIENCE 
BANGKOK, THAILAND 

1961 



PUBLICATION COMMITTEE 

and 
EDITORIAL STAFF 

Chairman: DR. CHARNG RATANARAT 
Vice-Chairman: M.R. CHAKRATONG TONGYAI 

MR. WELLINGTON BRINK PROF. NOPAKHUN TONGYAI 

MR. D. V. SASSOON MRS. CATHERINE F. SIFFIN 

MR. PUE ROCHANAPURANANDA DR. LYDIA NA RANONG 

MRS. M. ISABELLE FARRAR, Secretary 



PRINTED AT THAI WATANA PANICH, (R.O.P.), RAMA I ROAD, BANQKOK. BQONPRINQ T. SUWAN, PRINTER. B.B. 2504. 



CONTENTS 

Editor's Note i 

Abbreviations ii 

Participants iii 

Standing Committee Report 1 

MEINKOTH, NORMAN A., A Preliminary Report on a Collection of Littoral Invertebrates from 

the Vicinity of the Chulalongkorn University Marine Biological Station 2 

TAYLOR, EDWARD HARRISON, Some Factors Influencing Distribution and Speciation in the 

Lizard Genus Eumeces (Abstract) 5 

Symposium on Ecology and Pacific Distribution of the Giant African Snail with Special Reference 
to the Measures that are being taken for its Control 

MEAD, ALBERT R., A Prognosis in the Problem of the Giant African Snail (Achatina fulica 

Bowdich) 7 

PETERSON, JR., GEORGE D., Studies on Control of the Giant African Snail on Guam 

(Abstract) 11 

Symposium on Present Status of our Scientific Knowledge of Rodent Pest in the Pacific Area with 
Special in the Control of Rats and of Plague 

SEARLE, A.G. and DHALIWAL, s.s., The Rats of Singapore Island 12 

WATSON, J.s., Rats in New Zealand: A Problem of Interspecific Competition 15 

STRECKER, ROBERT L., Pacific Island Rat Ecology Project (Abstract) 18 

HARRISON, J.L., Ecology of the Forms of Rattus Rattus in the Malay Peninsula 19 

CHRISTIAN, JOHN j. and DAVIS, DAVID E., The Biological Basis of Rodent Control 25 

CLARK, R.J. Observations on the Rat Infestation of Cotabato, the Philippines 34 

QUAN, S.F., KARTMAN, L. and PRINCE, P.M., Recent Ecological Studies on Plague in Wild Rodents 

in Northern San Mateo County, California 44 

KARTMAN, LEO, An Insecticide-Bait Box Method for Plague Control in Certain Areas of the 

Pacific Region 49 

GROSS, BERTRAM, Observations on Rodent Plague in Hawaii (Abstract) 53 

THAINEUA, MALI, Plague in Thailand (Abstract) 54 

Symposium on Contributed Papers in Zoology 

UMESAO, TADAO, Japanese Expeditionary Activities in Biological Sciences in Postwar Asia ... 55 

KAWAMURA, SYUNZO, Field Studies on the Social Life of Primates in Japan 60 

LIANG, HSU-MU, Cycle Changes of Mouse Epidermal Cellular Population in Correlation with 

the Hair Follicular Activity 66 

BRONGERSMA, L.D., Zoological Exploration of Netherlands New Guinea 68 

MUNROE, EUGENE, Geography and Systematic Research 72 

GURJANOVA, EUPRAXIE, Comparative Research of Biology of the Littoral in the Far Eastern 

Seas 75 



EDITOR'S NOTE 

At the meeting of the Committee on Publications of the Ninth Pacific Science Congress, it was 
agreed that the increasing number of communications and papers presented at each Congress has 
become a very difficult problem for the Publication Committee and the editorial staff to cope with and 
that too much time is required to complete the publication of the Proceedings; therefore, it was recom- 
mended that the following principles governing publication be followed: 

a. That invited contributions to the scheduled symposium be published in full ; 

b. That reports of the Standing Committees be published in full; 

c. That other papers submitted to the Congress during its sessions be published in abstract only, 
the abstract not to exceed 500 words ; 

d. That papers which, though listed on the program or included in the pre-Congress abstracts 
published in advance but not actually submitted to the Congress at its sessions, should be 
disregarded; 

e. That authors be asked to indicate by a definite and early date 1 whether they prefer to publish 
their papers in sources other than the Congress Proceedings; that if this is done, the Congress 
should be acknowledged; 

f. That all proof reading be the responsibility of the editorial committee, and that this committee 
shall consider the manuscripts in their hands by a definite date as final; 2 

g. That authors be held responsible for submitting their material in good English; 

h. That on matters arising during the course of publication and not specifically covered in the 

statement of policy the editorial committee is empowered to act. 

In accordance with the resolutions of the Committee, the editorial board has edited the reports and 
manuscripts where necessary to bring uniformity and consistency to the format. Typographical and 
grammatical errors as well as errors in phraseology, spelling, or technical terms have been corrected, 
wherever possible, but in cases where the exact meaning of the original copy was not clear, the text has 
been left as submitted by the author. 

In order to reduce the cost and bulk of the publication, appendices, illustrations, and exhibits when- 
ever considered not vital to the text have been eliminated. 

If an author requested to publish elsewhere, his paper has been mentioned in the footnote under 
the respective titles, but if an author who presented a paper at the Congress failed to submit his manu- 
script either in full or in abstract, his paper and the discussions thereon have been eliminated entirely. 

It was also decided that, in order to complete the publication of the Proceedings as soon as possible, 
each division be published in a separate volume. Short volumes or the ones that do not require too much 
editorial work will be released first. Therefore, among the twenty volumes planned, any volume may 
appear first. They will not appear in consecutive order. 

The editorial board wishes to thank all authors who were prompt in submitting their revised manu- 
scripts in good form and, in particular, members of the Standing and Organizing Committees, too 
numerous to be named, who have helped in collecting the manuscripts pertaining to their respective 
divisions. 

The Board wishes in particular to thank Dr. F. Raymond Fosberg for going over and correcting 
the Special Symposium on Climate, Vegetation, and Rational Land Utilization in the Humid Tropics 
under Unesco; 

Mr. Saman Buravas of the Royal Mines Department for helping by redrawing charts and maps 
in order that they might reproduce clearly when printed; 

Mr. J. Alan Tubb of the FAO Regional Office, for his assistance in going over and clarifying some 
of the papers in the Fisheries and Oceanography volumes and in translating some of the French papers; 

Dr. Pradisth Cheosakul of the Department of Science for editing the Chemistry in the Development 
of Natural Resources volume; 

Last but not least, the Board wishes to thank the Thai Watana Panich Press for their cooperative ef- 
forts, far beyond the requirement of the contract, in devoting all their resources to printing these volumes. 



1 January 1, 1958, in the case of the Ninth Congress. 

2 March 1, 1958, in the case of the Ninth Congress. 



ABBREVIATIONS 



APFC 

CAA 

CSIRO 

ECAFE 

EQUAPAC 

FAO 

IACOMS 

ICA 

ICAO 

ICSU 

IOY 

IPFC 

IRC 

JCRR 

NORPAC 

PHILCUSA 

PIOSA 

SEATO 

SPC 

UN 

UNESCO 

UNICEF 

USDA 

USIS 

USOM 

WHO 

WMO 



Asia-Pacific Forestry Commission 

Civil Air Administration 

Commonwealth Scientific and Industrial Research Organization (Australia) 

Economic Commission for Asia and the Far East 

Equatorial Pacific (oceanographic survey) 

Food and Agriculture Organization 

International Advisory Committee on Marine Sciences 

International Cooperation Administration 

International Civil Aviation Organization 

International Council of Scientific Unions 

International Geophysical Year 

Indo-Pacific Fishery Commission 

International Rice Commission (FAO) 

Joint Commission on Rural Reconstruction (Taiwan, China) 

North Pacific (oceanographic survey) 

Philippine Council for United States Aid 

Pan-Indian Ocean Scientific Association 

South-East Asia Treaty Organization 

South Pacific Commission 

United Nations 

United Nations Educational, Scientific and Cultural Organization 

United Nations International Children's Emergency Fund 

United States Department of Agriculture 

United States Information Service 

United States of America Operations Mission 

World Health Organization 

World Meteorology Organization 



PARTICIPANTS 

ALFRED, ERIC RONALD, Zoologist, Raffles Museum, Singapore. 

AUDY, JACK RALPH, Division of Virus Research and Medical Zoology, Institute for Medical Research, 
Kuala Lumpur, Federation of Malaya. 

BAL, DATTATRAYA VAMAN, Director, The Institute of Science, Mayo Road, Bombay 1, India. 

BLINKS, LAWRENCE R., Professor of Biology, Stanford University, Hopkins Marine Station, Pacific 
Grove, California, U.S.A. 

BOLIN, ROLF L., Professor of Zoology, Stanford University, Hopkins Marine Station, Pacific Grove, 
California, U.S.A. 

BRITTAN, MARTIN R., Associate Professor of Life Sciences, Sacramento State College, Sacramento, 
California, U.S.A. 

BROMHALL, JOHN DEREK, Chief Scientific Officer, Fisheries Research Unit, University of Hong Kong, 
Hong Kong. 

BRONGERSMA, LEO DANIEL, Lecturer, Rijksmuseum van Natuurlijke Historic, Leiden, Netherlands. 

CANTELO, WILLIAM w., Staff Entomologist, U.S. Navy (Agana, Guam), FPO Navy No. 926, San 
Francisco, California, U.S.A. 

CHRISTIAN, JOHN JERMYN, Physiologist, Naval Medical Research Institute, Bethesda 14, Maryland, 
U.S.A. 

CLARKE, GEORGE L., Associate Professor of Zoology, Harvard University and Woods Hole Oceano- 
graphic Institution, Cambridge, Massachusetts, U.S.A. 

COOLIDGE, HAROLD JEFFERSON, Executive Director, Pacific Science Board, National Academy of 
Sciences, 2101 Constitution Avenue, Washington 25, D.C., U.S.A. 

COWAN, IAN MCTAGGART, Head, Department of Zoology, University of British Columbia, Vancouver 
8, B.C., Canada. 

DEIGNAN, HERBERT GiRTON, Associate Curator of Birds, Smithsonian Institution, Washington 25, 
D.C., U.S.A. 

FEHLMANN, HERMAN ADAiR, Assistant Curator, George Vanderbilt Foundation, Natural History 
Museum, Stanford University, Stanford, California, U.S.A. 

GIBSON-HILL, CARL ALEXANDER, Director, Raffles Museum, Singapore 6. 

GROSS, BERTRAM, Chief Bureau of Rodent Control, Division of Sanitation, Territorial Department of 
Health, Honolulu, Hawaii. 

GURJANOVA, EUPRAXIE, Head, Laboratory of the Zoological Institute, Academy of Sciences of the 
USSR, Leningrad, USSR. 

HARDY, ALISTER (^LAYERING, Professor of Zoology, Department of Zoology and Comparative Anatomy, 
University Museum, Oxford, England. 

HARRISON, JOHN LEONARD, Zoologist, Institute for Medical Research, Kuala Lumpur, Federation of 
Malaya.* 

HARRY-ROFEN, ROBERT REES, Research Director, George Vanderbilt Foundation, Natural History 
Museum, Stanford University, Stanford, California, U.S.A. 

HIATT, ROBERT w., Dean of the Graduate School and Director of Research, University of Hawaii, 
Honolulu 14, Hawaii. 

* Queensland Institute of Medical Research, Herston Road, Herston N. 9, Brisbane, Queensland, Australia. 

iii 



HORMCHONG, TWEE, Instructor, College of Education, Ministry of Education, Bang Saen, Thailand. 

HORSTADIUS, SVEN, Professor of Zoology, Zoological Institute, University of Uppsala, Uppsala, 
Sweden. 

KAWAMURA, SYUNZO, Lecturer, Institute of Polytechnics, Osaka City University, 12 Minami-ogimachi, 
Kitaku, Osaka, Japan. 

KHAN, M.R., Assistant Fisheries Officer, FAO Regional Office for Asia and the Far East, Bangkok, 
Thailand. 

LEKAGUL, BOONSONG, Physician, Sahakarnbhaet Clinic, Bangrak, Bangkok, Thailand. 

LIANG, HSU MU, Professor and Head, Biomorphic Department, National Defense Medical Center, 
Taipei, Taiwan, Republic of China. 

LINDSEY, CASIMIR CHARLES, Assistant Professor, Institute of Fisheries, University of British Columbia, 
Vancouver 8, B.C., Canada. 

LYNSDALE, JEAN A., Professor of Zoology and Dean of Science, Zoology Department, University of 
Rangoon, Rangoon, Burma. 

MCCLURE, H. ELLIOTT, Medical Ornithologist, 406 Medical Laboratory (U.S. Forces, Japan), APO 
343, San Francisco, California, U.S.A. 

MACFARLANE, w.v., Professor of Physiology, University of Queensland, Brisbane, Australia.* 

MEAD, ALBERT RAYMOND, Professor and Head, Department of Zoology, University of Arizona, Tucson, 
Arizona, U.S.A. 

MEINKOTH, NORMAN A., Fulbright Foundation Lecturer, Department of Biology, Chulalongkorn 
University, Bangkok, Thailand.** 

MEYER, KARL F., Director, Hooper Foundation, University of California Medical Center, San Fran- 
cisco 22, California, U.S.A. 

MILLER, ROBERT c., Director, California Academy of Sciences, San Francisco 18, California, U.S.A. 

MILTON, OLIVER M.B., Conservation Specialist, Peabody Museum, Yale University, New Haven, 
Connecticut, U.S.A. 

MUNROE, EUGENE GORDON, Principal Entomologist, Insect Systematics and Biological Control Unit, 
Entomology Division, Science Service, Department of Agriculture, Ottowa, Canada. 

MURPHY, ROBERT CUSHMAN, Research Associate (Curator Emeritus), American Museum of Natural 
History, New York 24, New York, U.S.A. 

PEMBERTON, CYRIL EUGENE, Experiment Station, Hawaiian Sugar Planters' Association, Honolulu, 
Hawaii. 

ROZEBOOM, LLOYD EUGENE, Associate Professor, The Johns Hopkins University, 615 North Wolfe 
Street, Baltimore 5, Maryland, U.S.A. 

SACHET, MARIE-HELENE, Bibliographer, Pacific Science Board, National Research Council, 2101 Con- 
stitution Avenue, Washington 25, D.C., U.S.A. 

SEARLE, ANTONY GILBERT, Lecturer in Zoology, Department of Zoology, University of Malaya, Cluny 
Road, Singapore 10. 

STEINHAUS, EDWARD A., Professor, Laboratory of Insect Pathology, University of California, Berkeley 
4, California, U.S.A. 

STRECKER, ROBERT LOUIS, Zoologist (Pacific Science Board), Ponape, East Caroline Islands, U.S. 
Trust Territory of the Pacific. 

* Australian National University, Canberra, A.C.T., Australia. 
** Department of Biology, Swarthmore College, Swarthmore, Pennsylvania, U.S.A. 

iv 



SUNDERLAND, SYDNEY, Dean, Medical School and Professor of Anatomy, Anatomy Department, 
Medical School, University of Melbourne, Carlton N. 3, Victoria, Australia. 

SZENT-IVANY, JOSEPH JULIUS HUBERT, Entomologist, Department of Agriculture, Stock and Fisheries, 
Port Moresby, Papua. 

TAYLOR, EDWARD HARRISON, Fulbright Foundation Lecturer, Department of Biology, Chulalongkorn 
University, Bangkok, Thailand.* 

THAINEUA, MALI, Provincial Health Officer, Department of Health, Ministry of Public Health, Ubon, 
Thailand. 

TRAPIDO, HAROLD, Deputy Director, Virus Research Centre, 20 A Wellesley Road, Poona 1, India. 

UMESAO, TADAO, Assistant Professor, Osaka City University, 12 Minami-ogimachi, Kitaku, Osaka, 
Japan. 

VAJROPALA, KLOOM, Professor of Zoology, Department of Biology, Chulalongkorn University, Bang- 
kok, Thailand. 

VANIJ-VADHANA, suPACHAi, Professor and Head, Department of Biology, Chulalongkorn University, 
Bangkok, Thailand. 



' Snow Hall, University of Kansas, Lawrence, Kansas, U.S.A. 



ZOOLOGY 



Standing Committee Chairman: H. BOSCHMA 
Organizing Committee Chairman: SUPACHAI VANIJ-VADHANA 



Standing Committee Report 



Editor's Note Dr. H. Boschma, who was to have 
presented a formal report of the Standing Com- 
mittee on Pacific Zoology at this time, was ill, 
and could neither attend the Congress nor pre- 
pare the report. In its place Dr. L.D. Brongersma 
presented a report of his own preparation. 

Dr. Brongersma commented on the difficulties 
of -biological research, especially systematic, 
encountered by workers in smaller countries 



where there are inadequate library facilities and 
where obtaining specific references involves 
considerable effort. He commented upon the 
geographical position of Thailand with reference 
to the overlap of northern and southern faunas, 
and stressed the desirability of intensive, com- 
prehensive and continuing systematic work by 
persons in academic, government, and private 
positions. 



PROCEEDINGS OF THE NINTH PACIFIC SCIENCE CONGRESS 



A PRELIMINARY REPORT ON A COLLECTION OF LITTORAL 
INVERTEBRATES FROM THE VICINITY OF THE CHULALONGKORN 
UNIVERSITY MARINE BIOLOGICAL STATION 

NORMAN A. MEINKOTH 

Fulbright Foundation Lecturer, Department of Biology, Chulalongkorn University, Bangkok, Thailand^ 



Chulalongkorn University completed con- 
struction of the first of a projected group of build- 
ings for its Marine Biological Station in January, 
1957. This station is located at Ang Sila (also 
known as Ang Hin) on the east shore of the 
Gulf of Thailand in Cholburi Province, about 
100 kilometers southeast of Bangkok. The 
initial building includes living facilities for a small 
complement of personnel, a laboratory room, 
a running fresh-water system, and electricity. 
A caretaker lives on the premises. The littoral 
habitats in the immediate vicinity include rocky 
shores, sand beaches, mixed sand, mud and rocky 
bottoms, and mud flats. The water is quite turbid 
due to the effluence of the Bang Pakong River, 
the Chao Phya River and lesser streams that 
flow into the northeastern part of the Gulf of 
Thailand. Salinity fluctuations in the vicinity of 
the station have not as yet been determined, 
but it is presumed that the dilution of sea water 
by the rivers is considerable. 

It seemed advisable to begin operations at the 
new station by undertaking a survey of the 
available marine invertebrate fauna. In the ab- 
sence of more sophisticated collecting apparatus 
or a boat, collections were made by fine-mesh 
dipnet, by walking along the shores at low tide 
and taking specimens by hand, and by digging 
sand and mud with a spade and sifting it through 
a bamboo sieve of approximately 0.3 mm. 
square mesh. This last item is a common com- 
modity in any Thai market. Specimens were 
placed in vials, jars or buckets of sea water and 
returned to the laboratory. Many were relaxed 
in a mixture of sea water ethanol (ethyl alcohol), 
sea water containing 8 % MgCl 2 , or a combination 
of these, prior to killing and preserving in 10% 
formalin or 70% ethanol. Some were relaxed 
and then killed in Bouin's fixing solution for 
future sectioning. The specimens were taken to 
the laboratory of the Department of Biology at 
Chulalongkorn University for identification and 
cataloging. 

At this point the author wishes to express his 
appreciation of the help and cooperation of 



Prof. Supachai Vanij-Vadhana, Head of the 
Department of Biology and Secretary-General 
of Chulalongkorn University, whose efforts are 
largely responsible for the existence of the 
Marine Station, and to Mr. Twesukdi Piyakarn- 
chana and Mr. Sunthorn Suanraksa, Instructors 
in Biology at Chulalongkorn, colleagues whose 
help as collectors and interpreters was indispen- 
sible. 

At present some of the specimens have been 
determined to genus or family, others only to 
order or class due both to the exigencies of time 
and the unavailability of the necessary taxonomic 
references. No attempt at all is made here to 
designate species, a job for taxonomic specialists 
and future effort. Below is a list of animals 
collected on trips made between August 3 and 
September 1, 1957. The second column from the 
right indicates relative abundance. For our 
purposes, rare is employed to indicate 1 to 9 
specimens taken, common will indicate 10 to 100 
taken or available for collection, and abundant 
will indicate numbers from over 100 to many 
thousands collected or available for collection. 
No attempt is made here to indicate habitats in 
which the animals were found. 

Porifera 

Class: Demospongia 
Subclass: Monaxonida 3 species abundant 

Cnidaria 
Class: Hydrozoa 
Class: Scyphozoa 

Order: Rhyzostomeae 
Class: Anthozoa 

Order: Actiniaria 

Order: Madreporaria 

Ctenophora 
Class: Tentaculata 

Order: Cydippida 
Class: Nuda 

Order: Beroida 

Platyhelminthes 
Class: Turbellaria 
Order: Polycladida 
Family: Prosthiosto- 
midac 1 sp. rare 



4 sp. (medusae) common 
1 sp. abundant 

3 sp. common 

1 sp. 

(solitary coral) common 

Pleurobrachia sp. common 
Beroe sp. common 



t Department of Biology, Swarthmore College, Swarthmore, Pennsylvania, U.S.A. 



VOLUME 19 



ZOOLOGY 



Nemertea 




Order: Decapoda 


Class: Anopla 




Family: Crangonidac Crangonsp. common 


Order: Heteronemertea 




Family: Palaemonidae Palaemonetes sp. common 


Family: Lineidae 


Cerebratulus sp. rare 


Family: Porcellanidae Polyonyxsp. common 




Micrura sp. rare 


other sp. common 


2 species of other families 


Family: Albuneidae Albuneasp. rare 






Family: Paguridac 2 sp. common 


Ectoprocta 




Family: Cancridae Cancer sp. rare 


Class: Gymnolaemata 




Family: Portunidae 5 sp. common 


Order: Cheilostomata 




Family: Pilumnidae 2 sp. common 


Family: Membrani- 




Family: Grapsidae 1 sp. common 


poridae 


Membranipora sp. common 


Family: Pinnotheridae 1 sp. common 






Order: Stomatopoda 


Brachiopoda 




Family: Squillidae 1 sp. common 


Order: Ecardines 






Family: Lingulidae 


Lingula sp. rare 


Chaetognatha 






Family: Sagittidae Sagitta sp. rare 


Annelida 






Class: Polydhaeta 




Echinodermata 


Family: Polynoidae 


Lepidonotus sp. rare 
Eunde sp. rare 


Class: Asteroidea 
Family : Astropectenidae Astropecten sp. rare 


Family: Sigalionidae 


Stheneldls sp. rare 


Class: Echinoidea 


Family: Nereidae 


Nereis sp. common 


Order: Clypeastroidea 1 sp. common 


Family: Glyceridae 


Glycera sp. common 


Class: Ophiuroidea 


Family: Onuphidae 


Diopatra sp. common 


Order: Ophiurae Orchasterias sp. common 




1 other sp. common 


1 other sp. common 


Family: Spionidae 


Dispio sp. common 


Class: Holothuroidea 




Polydora sp. rare 


Order: Dendrochirota 1 sp, rare 


Family: Magelonidae 


Magelona sp. rare 




Family: Capitellidae 
Family: Maldanidae 


Notomastus sp. common 
Euclymene sp. common 


Chordata 
Subphylum: Hemichordata Balanoglossussp. common 




] other sp. common 


Subphylum: Urochordata 2 sp. (colonial) common 


Family: Pectinariidae 


Pectinaria sp. rare 




Family: Terebellidae 


Amphitrite sp. rare 


DISCUSSION 




2 other sp. rare 




Family: Sabellidae 
Family: Serpulidae 


1 sp. rare 
Hydroides sp. common 
1 other sp. common 


Dr. Taylor asked whether turbidity and fluc- 
tuating salinity may influence the composition of 


Class: Sipunculoidea 


5 sp. common 


marine communities in the vicinity of the Marine 


\/f /-vlliieoo 




Biological Station. Dr. Meinkoth stated that 


Moiiusca 
Class: Gastropoda 
Family: Nassidae 


1 sp. abundant 


turbidity certainly excludes or impedes forms 
dependent upon light for orientation and naviga- 


Family: Neptunidae 


1 sp. rare 


tion, and probably excludes certain filter feeders 


Family: Thaisidae 
Family: Muricidae 
Family: Littorinidae 


2 sp. common 
Murex sp. rare 
1 sp. abundant 


not tolerant of mud. Conversely it favors other 
forms well adapted to muddy environments. He 


2 other families 




remarked on the well known restrictions inflicted 


Class: Pelecypoda 




by varying salinities on stenohaline organisms. 


Family: Tellinidae 
Family: Solenidae 
Family: Ostreidae 


1 sp. common 
Ensis sp. common 
Ostrea sp. abundant 


Dr. Mead commented on the similarity of the 
forms listed with those of more northerly waters. 


Family: Mactridae 


1 sp. abundant 


Dr. Meinkoth agreed that in the upper part of the 


Family: Veneridae 
Family: Mytilidae 
Family: Arcidae 
Family: Teredonidae 


1 sp. rare 
Mytilus sp. abundant 
Area sp. rare 
Teredo sp. common 


Gulf of Thailand many of the typical tropical 
invertebrates are absent, while those present are 
similar to a more northerly fauna. But he 


Class: Scaphopoda 
Family: Dentaliidae 


Dentalium sp. rare 


warned that since he is better acquainted with the 
northern forms his list tends to include those 


Class: Cephalopoda 
Family: Sepiidae 


Sepia sp. common 


among the genera already identified, while the 
less familiar ones, in the absence of available 


Arthropoda 




literature, have not as yet been identified. 


Class: Crustacea 
Subclass: Cirripedia 




Dr. Gurjanova commented that the list did 


Family: Balanidae 


Balanussp. abundant 


not agree with his previous concepts as to what 


Subclass: Malacostraca 
Order: Mysidacea 
Order: Isopoda 


several sp. common 
1 sp. common 


tropical seas might be expected to include. 
Dr. Brongersma, referring to his earlier state- 


Order: Amphipoda 


several sp. common 


ment about the paucity of source literature in 






3 



PROCEEDINGS OF THE NINTH PACIFIC SCIENCE CONGRESS 



libraries of smaller countries, asked members 
to contribute and get their colleagues to contri- 
bute to the Chulalongkorn University Biology 
Library. He began by presenting Professor 
Supachai with several reprints of papers published 
by the Leiden Museum referring to the fauna 
of Thailand. 

Dr. Mead asked who would ultimately identify 
the various parts of the collection. Dr. Mein- 
koth stated that he is continuing to solicit the aid 
of systematists in various museums and countries 
to undertake the determination of the various 



groups, and urged members present to make such 
suggestions as they may have regarding possible 
specialists who could and would cooperate. 

Dr. McT. Cowan, seconded by Dr. Mead, then 
moved that a resolution be prepared to be 
presented at the next meeting urging govern- 
mental authorities in Thailand to recognize the 
need for extensive systematic work on the fauna 
of this country, and to provide the continuing 
financial support for its implementation. The 
motion was passed. 



VOLUME 19 



ZOOLOGY 



SOME FACTORS INFLUENCING DISTRIBUTION AND SPECIATION 
IN THE LIZARD GENUS EUMECES 



EDWARD HARRISON TAYLOR 

Fulbright Foundation Recturer, Department of Biology, Chulalongorn University, Bangkok, Thailand. 

(Abstract) 



The cosmopolitan lizard genus Eumeces with 
some 60 to 70 recognized species and subspecies, 
represents one of the most plastic and progressive 
groups in the Family Scincidae. It would appear 
however that there are two groups within the 
genus, one, which I believe to be the older, has 
representative species in northwestern India, 
western Asia, north Africa, and three species 
(managuae, schwartzei, and altamirani) in south- 
ern Mexico and Central America; the other 
younger one occupies China, Japan (and sur- 
rounding islands), North America south to 
Mexico and northern Central America. 

The only other genus in the Scincidae having a 
large number of species (perhaps 83), that are of 
somewhat comparable size, cosmopolitan in 
distribution, and successful in maintaining large 
populations, is the genus Mabuya. 

Where these two genera come together they 
tend to become competitors for the same kind 
of food, the same ecological habitats, and one or 
the other seems to yield territory and they tend to 
become mutually exclusive. 

The area of eastern Asia (chiefly China and 
Japan) has a number of species of Eumeces while 
only a single species of Mabuya occupies territory, 
this in the southern part of the region; and no 
species of that genus occurs over a great part of 
the territory where there are several species of 
Eumeces. 

In the Indo-Chinese area and eastern Thailand 
only a single species of Eumeces is known, and 
here the species is rare, while several species of 
Mabuya thrive. In western Thailand, the Malay 
Peninsula, the Sunda Islands, and the Philippine 
Islands, and westward on the continent through 
Burma and peninsular India, not a single species 
of Eumeces exists; while numerous species of 
Mabuya occupy these areas and all appear to be 
highly successful. Neither genus has passed 
eastward beyond "Wallace's Line". 

In western Asia, and northern Africa from 
Egypt to Morocco, several species of Eumeces 
are known, while few or no species of Mabuya 



occur. South of the Sahara to the Cape, and on 
the great island of Madagascar there are numer- 
ous species of Mabuya, but the genus Eumeces 
is unknown. 

In southern Canada, the United States, Mexico 
and northern Central America there are numerous 
species of Eumeces, all presumably belonging to 
the younger group. One species even passes 
beyond the Isthmus of Tehuantepec into northern 
Central America. There also occurs in northern 
Central America and much of Mexico (except 
higher parts) a species of Mabuya, one that is 
eminently successful and seemingly has a pro- 
found effect on the species of Eumeces. Certain 
species of Eumeces, where the Mabuya also occurs, 
have become diminutive and no longer compete 
for the same food, while any larger forms of 
Eumeces occupy high mountainous areas where 
Mabuya probably cannot go. The three species 
of the older group are presumably able to com- 
pete with the Mabuya (all are larger), and they 
are not obviously affected by its presence. 

Reduction in size, lengthening of the body, and 
the reduction of the size of the limbs is a common 
expression of yielding to competition. Often 
survival depends on the reduction or complete loss 
of limbs, together with the assumption of a sub- 
terranean abode and at the same time, a food- 
habitat completely different. 

In summary, it would appear that Mabuya 
and Eumeces tend to exclude each other from 
food-habitats and range depending on the degree 
of dominance one may attain over the other. 
Sometimes the exclusion is not complete, as for 
instance Eumeces quadrilineatus in Thailand and 
Indo-China and Mabuya longicaudata in southern 
China; the presence of a single Mabuya in western 
Asia, or a single species in Mexico. 

No form of Eumeces is known to have suc- 
ceeded in becoming completely adapted to a 
subterranean existence. Nowhere does evidence 
show that Eumeces has succeeded in forcing 
Mabuya to change body form in order to survive, 
while the reverse is seemingly true. 

5 



PROCEEDINGS OF THE NINTH PACIFIC SCIENCE CONGRESS 



DISCUSSION 

PROF. SUPACHAI: What is the food for which the 
genera Eumeces and Mabuya compete? 

DR. TAYLOR: Typical insects such as small coleop- 
tera, small lepidoptera, and their larvae, diptera and their 
larvae, more rarely Isoptera and Hymenoptera. 

CHAIRMAN BRONGERSMA: Why do you regard 
Mabuya the more dominant genus of the family? 

TAYLOR : Often the greatest competitors for food and 
territory are closely related species. The fact that these 
forms tend mutually to exclude each other from certain 
areas show that dominance between the two groups is 
nearly balanced. I would suspect that in certain areas 
Eumeces becomes dominant and tends to exclude Mabuya 
completely. In other places Mabuya is dominent and is 
able to exclude Eumeces. In Mexico, however, one species 
of Mabuya has seemingly forced Eumeces to elevations in 
high mountains where Mabuya does not or cannot live. 



In areas where they occupy territory together the species 
of Eumeces are dwarfed, and otherwise modified. On the 
other hand there is no evidence that Mabuya has been 
similarly reduced. 

Dr. Taylor answered questions about the 
interpretation of the term dominance, and food 
of the members of the genera. 

Dr. Brongersma asked Dr. Taylor regarding 
his experience with Eumeces. Dr. Taylor replied 
that he had spent five years collecting and 
studying the species, preparing and publishing a 
monograph 1 on the genus, based on a detailed 
study of most of the Eumeces materials in Ameri- 
can museums and much in European museums. 
Dr. Brongersma remarked on the difficulties 
presented by this genus and commended Dr. 
Taylor for having undertaken the project. 



t A Taxonomic Study of the Cosmopolitan Scincoid Lizards of the genus Eumeces with an Account of the distribution and 
relationships of its species. University of Kansas Sci. Bull, vol. 23, 1936, pp. 1-643, plates 1-43, text figs. 1-84. 

6 



VOLUME 19 



ZOOLOGY 



Symposium: Ecology and Pacific Distribution of the Giant African Snail 
with Special Reference to the Measures that are being 
taken for its Control 



A PROGNOSIS IN THE PROBLEM OF THE GIANT AFRICAN SNAIL 

(Achatina fulica Bowdich)t 

ALBERT R. MEAD 

University of Arizona, Tucson, Arizona, U.S.A. 



Because Man is the prime vector of the giant 
African snail, because usually Man inadvertently 
carries the snails from place to place, and because 
Man is continually on the go, it is easy to predict 
that in spite of control and quarantine measures, 
this snail pest the largest major snail pest in the 
world will continue to be spread into many 
new areas within the next relatively few years. 

During the last century, Achatina fulica was 
taken from its East African home to the Masca- 
rine Islands and India. Since the turn of the 
century, it has traveled from Ceylon to most of 
Southeast Asia, fanning out in the Pacific to 
establish itself in a wide area from Hong Kong, 
Okinawa, and the Bonin Islands, to New Britain, 
Ponape, and the Hawaiian Islands. Actually, 
its frontiers have extended to Australia, Japan 
and continental United States; but fortunately 
because of interceptions and quarantine measures 
it has not become established in these areas. 
The question of prime concern is whether or not 
this giant snail has the capacity to establish 
itself in these and other uninfested areas. Little 
attempt has been made to answer this important 
question. Reasons for it rest in the fact that we 
know altogether too little about this animal far 
less than for almost any other major agricultural 
pest. Most importantly, we do not know to what 
extent this species is able to give rise to popula- 
tions containing at least a few individuals which 
have the physiological capacity to adjust to 
the reduced temperatures of the northern and 
southern temperate regions. The most northern 
population, in Ani Jima of the Bonin Islands 
(lat. 27 07' N), was found by Dr. Yoshio Kondo 
and myself to be in a thriving state. Apparently 
the threshold of minimum tolerance to cold has 
not yet been reached. The inordinate sensitivity 



of this snail to higher altitudes seems to stem not 
from the factor of cold alone but quite likely from 
intolerance to a diurnal temperature fluctuation 
beyond a point where to survive, it normally 
would need a period of several days to become 
conditioned physiologically. It is significant that 
snails are surviving colder winter temperatures 
at sea level in Ani Jima than they can at an 
altitude of 5,000 ft. in Ceylon. 

What we do know about the snail tells us 
that we are up against a remarkably hardy pest. 
It lives for at least five years. During this period 
of time, a single individual theoretically can give 
rise to over five quadrillion offspring. This snail 
can go for a year without food and water. Since it 
is a scavenger, it will accept as food almost an 
unlimited range of items. It will bury itself 
several inches below ground to escape the effects 
of cooler weather. It has exceedingly few natural 
enemies. It is essentially nocturnal and crepus- 
cular in its habits, hence escaping the rigors of 
diurnal life and escaping detection of its worst 
enemy Man until all too often it is inextricably 
established. Acid soils and their lack of available 
lime are no barrier; for the snail gets its lime sup- 
ply by scavenging on the fallen leaves of trees that 
have unlocked the bound calcium in the soil. 
As demonstrated so beautifully by Howes and 
Wells (1934) in other species, this snail irrespective 
of the nature of external conditions, is subject to 
periodic phases of estivation due to a physiolo- 
gical "hydration cycle." This permits at any time 
inaccessible, estivating individuals to restock 
an infested area after the effects of natural or 
man-made adverse conditions have dissipated. 
Knowledge of this phenomenon is of tremendous 
importance because it gives an explanation for the 
failures of even some of the most rigorous control 



t This is a preliminary report based on a manuscript, entitled: "Economic status, control, dispersal, and outlook in the 
problem of the giant African snail (Achatina fulica Bowdich)." The manuscript is being prepared under grants and funds 
From Sigma Xi-RESA and the National Science Foundation, Washington, D.C., (NSF-G519); and present research is 
being conducted under support of a U.S. Public Health Service Research Grant [E-l 245 (C) ] . 

7 



PROCEEDINGS OF THE NINTH PACIFIC SCIENCE CONGRESS 



measures and helps us understand why this pest, 
after becoming firmly established, has never been 
eradicated. And lastly, this snail species is 
genetically variable to the extent that each of 
the different types of environment, in which the 
snail has been able to establish itself, appears to 
have had a selecting effect upon the complement 
of character determiners that happened to be 
present in the original snail stock infesting the 
area. Undoubtedly, the high reproductive 
potential of the snail has considerably accelerated 
this process. The results are such that a taxono- 
mist, not knowing the whole story, would be 
tempted to designate the different types as distinct 
subspecies. We do not know the limits of genetic 
potentiality in producing still different and still 
more hardy individuals. 

There is little doubt in my mind that it is only a 
matter of time until Achatina fulica becomes 
essentially ubiquitous in the greater share of the 
Indo-Pacific region. Any uninvested island or 
coastal continental area in the Pacific region which 
has even a modest cover of vegetation and which 
falls between 30 North and 30 South latitude 
must be considered a potential site of establish- 
ment for the giant snail. This includes northern 
and much of eastern coastal Australia, as Harri- 
son (1951) agrees. Northern New Zealand and 
southern Japan lie in the peripheral regions where 
the possibility of successful establishment of this 
pest depends upon the genetic potentialities of 
producing more hardy types. Although my 
opinions have been challenged, I still feel certain 
that at least the southern part of California would 
be susceptible to invasion by this snail. The 
agro-climatic analogues established by Nutton- 
son (1952) support my earlier statements that the 
portion of the United States bordering the Gulf of 
Mexico is vulnerable to attack. It follows that 
much of the Neotropical region is similarly 
vulnerable. That the snail is not yet known 
to be established in the vast tropical areas of the 
Western Hemisphere is almost miraculous. The 
frontiers of invasion will be extended into desert 
and more temperate zones through Man's 
activities in building nurseries, greenhouses and 
desert gardens. 

Chemical control measures are for the most 
part expensive, impractical or only transitory in 
effect. A truly effective, economical molluscicide 
has yet to be found. The currently popular 
metaldehyde and calcium arsenate leave much 
to be desired. Actually, there is evidence that 
improper use of mulluscicides will bring about an 
increase rather than a decrease of the snail 

8 



population! Hand collecting and destroying is 
the most economical method of control and the 
one most often resorted to since the only expense 
involved is labor. Attempts to control the snails 
through legislative action are of limited value. 
Nonetheless, this "limited value" is absolutely 
indispensable in the overall program in providing 
a "holding action" until more effective control 
measures can be devised. Legislative action has 
been particularly effective in the Hawaiian Islands 
and California. There is little immediate hope 
for any appreciable controlling action through 
the use of the giant snail for human consump- 
tion; but experiments recently completed at 
the University of Arizona attest to the fact that 
the dried snail meal holds great promise as a 
poultry and livestock food supplement. Any 
extensive use for this purpose is certain to produce 
a controlling effect. 

The use of multiple predators in an attempt to 
control the giant snail is at present being tried on 
an impressive scale in the Hawaiian Islands. 
Although it is too early to make any predictions, 
the results are bound to be significant. No true 
parasite of A. fulica is known. However, a 
disease syndrome was found to be present in 
snails in Ceylon, Singapore, Hong Kong and 
Hawaii. The epizootiological picture suggests 
that it is a chronic disease, producing visceral 
and dermal lesions and reducing the life expectancy 
of the snails. The disease either goes into a fatal, 
acute stage later in the life of the host or has a 
decisive effect when there is a compounding of 
stress factors. A.U.S. Public Health grant is 
making it possible to conduct experiments in an 
attempt to determine the etiology, the pathogen- 
icity, and the effect of stress factors on the 
progress of the disease. 

It is felt that this disease plays the major role 
in the frequently observed and reported "decline" 
in the older populations of A. fulica. The 
decline is so pronounced in some sections of 
Ceylon that the giant snail appears to be virtually 
extinct. When a disease agent of sufficient vir- 
ulence builds up in a snail population that has 
passed through its normal sigmoid growth stage, 
the decline in the population is such that the snail 
ceases to be a major pest. Any subsequent 
recrudescence apparently is only partial. 

It is not impractical to entertain the idea of 
using a disease agent in the biological control 
of A. fulica. In contrast to a metazoan predator, 
it is possible for a microbiological agent to have 
the reproductive capacity, virulence and trans- 
missibility to produce a catastrophic and even 



VOLUME 19 



ZOOLOGY 



eradicative effect upon the host population. 
But unless the agent has a truly remarkable gene- 
tic stability, by the same token, it may produce 
strains with undesirable traits. Those who have 
worked with myxomatosis in Australia will 
vouch for this point. It goes almost without 
saying that before any use of a disease agent can 
be made safely, a tremendous amount of research 
must be done in close coordination with the 
microbiologist, the malacologist, the biological 
control man, and the naturalist. If Man is ever 
to eradicate the giant African snail on anything 
but the smallest scale, he will do it through the 
use of disease agents in conjunction with 
supplementary measures. 



REFERENCES 



(1) Harrison, T.H., 1951, The giant snail, Health, 

n.s. 1 (3):16-18. 

(2) Howes, N.H. and G.P, Wells, 1934, The 

water relations in snails and slugs, /. 
Exp. BioL, 11 (4):327-351. 

(3) Nuttonson, M.Y., 1952, Ecological crop 

geography and field practices of the 
Ryukyu Islands, natural vegetation of 
the Ryukyus, and the agro-climatic 
analogues in the northern hemisphere. 
Washington, D.C., Amer. Inst. of 
Crop EcoL, 106 p. 



DISCUSSION 



N.A. MEINKOTH: Have you ever eaten this snail? 

A.R. MEAD: Yes, but while edible it is not palatable. 
It has a strong humus flavor. 

H.M. LIANG : Japanese forces ate them during World 
War II. It is claimed that eating a large amount causes 
vomiting. 

A.R. MEAD : They are standard items of diet in Ghana 
and interior Taiwan. No distress is suffered. Excess snail 
meal in chick feed gives chicks diarrhea. But when they 
recover, they gain faster than control chicks. 

H.M. LIANG: They are used to feed ducks on Taiwan. 

J.L. HARRISON: They are thought in Malaya to give 
a bad taste to duck eggs and flesh. 

A.R. MEAD: There is convincing evidence that snails 
in the diet induce ducks to lay more eggs, and it is clearly 
shown they do not change the flavor of the eggs. 

J.L. HARRISON: Achatina in Malaya seems confined 
to cultivated areas and does not occur in the bush or 
forest. 

A.R. MEAD: It is an enigma why snails do not enter 
the native bush extensively. Yet they readily enter paces 
disturbed by man, and survive quite a while after he 
abandons it, but do not seem to penetrate far peripherally. 

J.L. HARRISON: In Malaya they survive in abandoned 
resettlement clearings for quite a while. 

A.R. MEAD: May I point out the genetic flexibility of 
these and other snails ? Dwarf populations occur in many 
places. Variation in the disease syndrome which I ob- 
served may be due to genetic differences in the snails or the 
disease agents, or both. Adaptibility is great, and envi- 
ronmental selection factors are also great, which results in 
great differences among populations. 

w.w. CANTELO: Many variations are noted in 
Micronesia. 

J.L. HARRISON: Is this genetic variation or simply 
lack of complex environmental selectivity? 

s. HORSTADIUS: Have any genetic studies been 
undertaken? 

A.R. MEAD: No, but they are contemplated for the 
near future. 

s. HORSTADIUS: Would it be valuable to make such 
experiments on a large scale? 



A.R. MEAD : Yes, it would. 

s. HORSTADIUS: In using snail-meal for chick feed, 
is there any use to which the shells can be put? 

A.R. MEAD: Yes, they are used in the chick feed to 
some extent. In places they are buried. But they may 
have a profound effect on soil pH to the disadvantage of 
certain crops, such as tea. 

C.E. PEMBERTON: Are there any other diseases useful 
in control of Achatinal 

A.R. MEAD: Practically nothing is known about this 
subject. A few papers are published on apparent gas- 
tropod pathogenesis, but results do not rule out senescence 
or malnutrition. 

E.A. STEINHAUS: In France, there is an Aerobacter 
infection in cultured Helix. 

A.C. HARDY: Are electric fences used to keep snails 
out of areas? 

A.R. MEAD: Although this would work, it is not a 
practicable procedure. 

A.C. HARDY: Are there any natural bird predators in 
Africa, especially those eating eggs or young? 

A.R. MEAD: Many birds do, but avian predators are 
categorically ruled out because of other considerations. 

R.L. STRECKER: On Ponape a decline in the snail 
population followed the introduction of the barrier fence. 
The question is, how good are census methods? 

A.R. MEAD: Sound sampling methods have been 
developed and tested. 

FURTHER COMMENT: Achatina has been known in 
Ceylon for 50 years. The disease has recently built up, 
and snails are disappearing locally. In Hawaii the disease 
incidence rose from 17% to 56% in three years. If the 
disease along with environmental stress reduces the popula- 
tion, the snails should cease to be a major pest. 

R.L. STRECKER: I question the value of the carnivo- 
rous snail Gonaxis in control. 

A.R. MEAD: Its value is not proved. Where Gonaxis 
has been introduced Achatina has declined, but populations 
of Achatina have also declined where Gonaxis was not 
introduced. The question remains as to how to evaluate 
Gonaxis. 



PROCEEDINGS OF THE NINTH PACIFIC SCIENCE CONGRESS 



How long have the giant snails been 



C.E. PEMBERTON: 
onAgiguan? 

A.R. MEAD: It is believed that they were introduced 
in 1946 or 1947, but it may have been somewhat earlier. 

w.w. CANTELO: Were they on Saipan and Tinian 
before the war? 

A.R. MEAD: Yes. They came to Saipan about 1938. 
They were brought to Guam about 1946. These snails 
were introduced for use in primitive medicine, later got 
loose and became pests. The same thing happened in 
Hawaii; they were advertised by Japanese enterpreneurs 
and sold. 

E. OURJANOVA: During the war a large marine snail 
was introduced into the Black Sea, its eggs deposited on 
ship hulls. It now is very abundant. 

A.R. MEAD: This is comparable to Achatina; also to 
the introduction of the marine snail Littorina littorea in 
many parts of the world. 

s. VANU-VADHANA: What is the pest status of Acha- 
tina in Malaya? 
j. L. HARRISON : It does not seem to be a serious pest. 

s. VANU-VADHANA: That seems to be the case in 
Thailand. 

A.R. MEAD : It is recent in Thailand. In Malaya it was 
not a pest at first, later became a serious pest in some 
places, but now has subsided considerably. 



It seems to have reached an equili- 
This is the history of growing populations 



j. L. HARRISON: 
brium. 

A.R. MEAD: 
of all kinds. 

w.w. CANTELO: Populations are subsiding on Guam 
and Marianas. We no longer find giant forms, more medi- 
um sized ones. People put bait out in open places, attract 
snails out where sun can kill them. I think the problem 
is vastly overrated. 

A.R. MEAD: This thinking is common, and in some 
places justified. Nevertheless under certain circumstances 
it can be a very serious problem. There is no need to 
panic, but the problem should not be underrated. In 
Ceylon they seriously damage cacao seedlings, and many 
other young plants while ignoring adult plants of the same 
species. 



R.L. STRECKER: Is the disease in Hawaii the same as 
elsewhere? 

A.R. MEAD: Not certain; there are some differences, 
but these may be strain differences. 

C.E. PEMBERTON: All Achatina in Hawaii are the 
progeny of 1 1 snails. The disease must have been brought 
in with them unless it is of another source. 

A.R. MEAD: The origin of the disease not certain. 
It may have come from Africa, but it probably came from 
Ceylon and India. It is chronic, not acutely fatal, but fatal 
under stress conditions. Now we must find these stress 
conditions. 

w.w. CANTELO: Does the disease really shorten 
their lives? 

A.R. MEAD: This is the only logical conclusion 
I can reach. In Ceylon, where they have been established 
for 50 years, I can only find 2 and 3 year old snails, while 
elsewhere they may live 5 to 6 years. 

At this point Dr. JJ.H. Szent-Ivany of the 
Department of Agriculture, Stock and Fisheries, 
Port Moresby, Territory of Papua and New 
Guinea, came in to comment on the work of a 
colleague, Dr. Bridgeland. In New Britain 
Achatina has become widespread and a great 
pest with cacao seedlings. The seedlings were 
circumscribed with a ring of methaldehyde in 
paraffin oil spread on the soil. It was very 
effective in attracting and killing the snails. But 
the process is uneconomical in the rainy season 
when it has to be repeated frequently. 

He noted that on New Guinea the snails have 
not spread so fast as on New Britain, where the 
snails seem to be getting smaller and smaller, 
with none of the big ones remaining. The shells 
seem to be weaker, as shown by the ease with 
which they crush underfoot. 

A.R. MEAD: Where populations are fulminating they 
do great damage. Persons coming into an area at a later 
time completely miss the crux of the real problem. When 
Achatina comes into equilibrium with various environ- 
mental factors it becomes a much smaller problem. 



10 



VOLUME 19 ZOOLOGY 

STUDIES ON CONTROL OF THE GIANT AFRICAN SNAIL ON GUAMt 

GEORGE D. PETERSON, JR.t 

Agricultural Extension Service, University of California, El Centra, California, U.S.A. 



(Abstract) 



The giant African snail, Achatina fulica Bow- 
dich, became established on Guam during World 
War II. An attempt in 1946 to eradicate the 
snails was unsuccessful. 

The following control investigations are 
described: 

Chemical controls: Sodium Arsenite; metaldehyde 
and calcium Arsenate; combined rat and snail 



bait; poisonous whitewash and wood ashes. 

Other artificial controls: Salt water and hand- 
picking; barriers. 

Biological control: Carnivorous snails (Gonaxis 
kibweziensis) ; Indian glowworm (Lamprophorus 
tenebrosus). 

Other natural enemies: Rats and coconut crabs; 
musk shrew; ducks. 



t Hilgardia 26 (16): 643-58. University of California, Berkeley, California; July, 1957. 

t Assistant Agriculturist, University of California Agricultural Extension Service, El Centre, California. (Formerly staff 

entomologists for the Guam Department of Agriculture from April, 1951, to May, 1955.) 



11 



PROCEEDINGS OF THE NINTH PACIFIC SCIENCE CONGRESS 



Symposium: Present Status of our Scientific Knowledge of Rodent Pest 
in the Pacific Area with Special Reference to the Control 
of Rats and of Plague 

THE RATS OF SINGAPORE ISLAND 



A.G. SEARLE and S.S. DHALIWAL 
Zoology Department, University of Malaya, Singapore. 



The island of Singapore lies only 1 20' North 
of the equator and covers an area of about 
200 square miles, being 27 miles long and 14 
miles wide. It is separated from the mainland 
of Johore by narrow straits about half a mile 
across. This isolation is lessened by two main 
factors: the wide causeway which now connects 
the island with the mainland of Malaya and the 
vast quantity of shipping visiting the port from all 
over the world. In the last 150 years there has 
been a rapid change in the island's ecological 
characteristics. Instead of being sparsely popu- 
lated and almost entirely covered by primary 
jungle, it now contains well over one million 
people while only a small patch of the original 
jungle is left. These changes have had a profound 
effect on the island's rats, leading to the extinction 
of some species, but the introduction and multi- 
plication of others, especially those human 
commensals which come under the heading of 
pests. They may also lead to evolutionary 
modifications of particular species, especially 
when combined with some degree of isolation. 
A detailed study of the island's rat population and 
its various components should be of interest 
to zoologists and others concerned with public 
health. By comparing the results with earlier 
reports from Singapore and with data from the 
mainland, we can obtain a dynamic (if somewhat 
speculative) picture of present trends and thus 
can predict future probabilities. The present 
investigation has involved trapping rats in a wide 
variety of habitats, from city fringe to secondary 
jungle; we have been greatly helped by the City 
Health Department and by Captain Jennings of 
the R.A.M.C. Hygiene Unit, who have kindly 
supplied us with rats from urban and other 
areas. 

Five species of Rattus have been recorded 
from Singapore, namely surifer, the spiny-backed 
rat; annandalei, or Annandale's rat; norvegicus, 
the brown rat; exulans (=concolor) 9 the little 
Burmese rat; and rattus itself. Rattus surifer 

12 



is a jungle species; its subspecies leonis was 
described by Robinson and Kloss from Singapore 
in 1911 but has been discovered nowhere else, 
suggesting that, despite its proximity to the main- 
land, the island has produced distinct forms. 
It seems doubtful whether Rattus surifer still 
survives on the island; we were unable to catch 
any. Sub-species leonis has been unable to adapt 
itself to the rapidly changing environment and 
is therefore on or over the verge of extinction. 

Rattus annandalei bullatus has a much softer 
fur than Rattus surifer, and looks rather like 
Rattus rattus jalorensis (the Malayan field-rat) 
except that it is larger, with a skull-length of 
47-48 mm. as a rule. It is quite common in some 
rural areas; we caught it in an old overgrown 
rubber estate, in belukar (scrub) and in the 
secondary jungle of the Nee Soon catchment 
area in the centre of the island. Rattus annandalei 
annandalei is known from near Kuala Lumpur 
in Malaya, but seems much less common there. 
Mainland specimens generally have a much 
whiter belly-color than Singapore ones which are 
cream or pale yellow. Thus there may be a 
North-South cline for ventral fur-color. Our 
Singapore specimens have a mammary formula 
of 2 + 2 = 8 while J.L. Harrison (1948) gives 
3 + 3 = 12 or 3 + 2 = 10 for those from the main- 
land. Intraspecific variation in mammary for- 
mula is usually rare; these differences suggest 
that more than one species may be involved. 
It is interesting to note that sub-species bullatus 
was originally recorded as a separate species, 
Mus villosus, by Kloss (1908). 

Rattus norvegicus is a pest in many parts of 
the world and was no doubt introduced into 
Singapore soon after its foundation. It is abun- 
dant in the city harbor area and streets adjacent 
to this, but is hardly ever found more than half 
a mile or so, inland. We have not found it at all 
in the rural parts of the island. This is in striking 
contrast to the situation in Europe, where Rattus 



VOLUME 19 



ZOOLOGY 



rattus is confined to dock areas but Rattus norve- 
gicus spreads throughout the countryside. 

In the city area, two other kinds of rat are 
found, namely Rattus rattus diardii (the Malayan 
house-rat) and Rattus exulans. All three species 
may be caught in the same street, but in this 
environment norvegicus seems at least three times 
as common as the other two species conbined, 
some figures by Gilmour (1934) show how 
common rats were in Singapore city even 50 
years ago. Well over 100,000 were destroyed 
each year, with a peak of 181,807 in 1908. Gil- 
mour observed that there were, on the average, 
more fleas on Rattus rattus in Singapore than on 
Rattus norvegicus, although the latter is much 
larger. We found, however, that about 40% of 
norvegicus rats had tapeworm cysts (Taenia 
echinococcus) on the liver, but only about 10% 
of rattus rats, while none were found on Rattus 
exulans. 

Rattus exulans is widely distributed on the 
island, not only in the city area and in kampongs 
outside the city, but also in belukar far away 
from any human habitation. We did not find 
it in secondary jungle. 

In the past, only form diardii of Rattus rattus 
has been reported from Singapore, where it 
seems to be much more variable than on the 
mainland. It occupies a wide range of different 
habitats, such as the city area, belukar, rubber 
plantations, mangrove edge and even in secondary 
jungle. It was found far away from any houses, in 
sharp contrast to the situation on the mainland, 
where it is replaced by form jalorensis in such 
habitats. Diardii also shows great variation in 
its ventral fur-color, which may be light brown, 
light grey, dark smoky grey, buffy white or nearly 
as white as the sharply defined underparts of 
jalorensis. This variation may have been due to 
the absence of jalorensis from the island, allowing 
diardii to spread into habitats which the former 
would normally be better adapted for, and, 
perhaps relaxing selection for one particular shade 



of ventral fur-color. Unlike all previous workers, 
however, we did discover jalorensis on the island. 
All came from a restricted coastal region of 
mangrove (containing Pandanus, Avicennia 9 Rhi- 
zophora, etc.) on the north side of the island about 
half a mile west of the Singapore- Johore cause- 
way. None were found in other favorable 
habitats such as belukar or secondary jungle, or 
in mangrove to the south of the island. Trapping 
on the mainland roughly opposite the jalorensis 
locality on the island produced more of the same 
form. These findings suggest that jalorensis is a 
recent addition to the Singapore fauna; in fact it 
may have spread to South Johore comparatively 
recently. Perhaps this is the start of a large scale 
invasion of the island by this form, but it may 
well be prevented from occupying its usual 
habitats by the prior presence of diardii. Singa- 
pore jalorensis show various differences from 
those of the Kuala Lumpur area; for instance, 
Singapore jalorensis have darker dorsal surfaces 
than Kuala Lumpur jalorensis and the dorsal 
stripe is more prominent in Singapore jalorensis. 

The Table gives the statistics of body and skull 
sizes in Singapore rats, which may be of interest 
to workers in other regions. Summing up, we 
can see that Singapore rats exhibit many interest- 
ing biological phenomena, mainly as a result of 
the rapidly changing environment. There is the 
extinction of one form (Rattus surifer) due to the 
destruction of its habitat; the spread of species 
commensal with Man, such as Rattus norvegicus 
and Rattus rattus; the spread of a form (diardii) 
into unusual habitats owing to the absence of 
competition; the recent appearance of a new 
form (jalorensis) in the area, with intra-specific 
competition as a probable result; the genetic 
differentiation of populations from those in 
adjacent regions, and so on. Continuing studies 
of the rat fauna of Singapore should help us to 
understand these processes and to find better 
methods of controlling these ever menacing 
rodent pests. 



Table. Adult Singapore rats: mean body and skull sizes in mm. with standard errors. 



Species 


Number 


Head + body 


Tail 


Hind-foot 


Rattus annandalei 


10 


198.03.3 


217.92.1 


37.8 0.6 


Rattus exulans 


26 


111.41.8 


128.9 2.4 


23.2 0.2 


Rattus norvegicus 


44 


222.7 3.1 


191.52.7 


42.1 0.3 


Rattus rattus diardii 


58 


184.4 1.7 


186.91.9 


35.20.2 


Rattus rattus jalorensis 


15 


176.9 2.6 


151.84.3 


32.7 0.3 



Ear 


Skull-length 


20.9 0.3 


47.7 1.2 


16.00.2 


30.3 0.4 


20.5 0.2 


47.2 0.5 


20.4 0.1 


41.50.2 


19.80.3 


40.6 0.9 



13 



PROCEEDINGS OF THE NINTH PACIFIC SCIENCE CONGRESS 



REFERENCES DISCUSSION 

Gilmour, C.C.B., 1934, Malayan Med. J. 9: J.L. Harrison commented on the microevo- 

177-81. lution of Rattus annandalei. Too few specimens 

Harrison, J.L., 1948, M.N.J. 2: 130. are available to be certain of its exact status, 

Kloss, C.B. 1908, J.F.M.S. Mus. 2: 146. but he suspected a cline from Kuala Lumpur 

Robinson, H.C. and Kloss, C.B., 1911, J.F.M.S. south to Singapore. 
4: 170. 



14 



VOLUME 19 



ZOOLOGY 



RATS IN NEW ZEALAND: 
A PROBLEM OF INTERSPECIFIC COMPETITION 

J.S. WATSON 

Animal Ecology Section, Department of Scientific and Industrial Research, New Zealand. 



New Zealand has three rat species: Rattus 
exulans brought to the country by the Polyne- 
sians about 700 years ago; and R. norvegicus, 
and R. rattus brought by the Europeans in the 
first half of the nineteenth century; norvegicus 
was associated particularly with whalers who 
established shore stations where rats became 
very numerous. Exulans has been widely dis- 
tributed over most of the country, but disap- 
peared rapidly from the North Island at the same 
time as norvegicus became common, and it was 
generally assumed that the latter had driven out 
the former. However, in the South Island exulans 
persisted for much longer, particularly in the 
forested parts of the north-west and perhaps also 
in the south-west. At irregular intervals these 
rats increased tremendously in numbers and 
hordes of them invaded the settled districts. 
These rat outbreaks were most probably corre- 
lated with years of prolific seeding of the beech 
trees (Nothofagus) in the forest, and certain forest 
birds, particularly the parakeets (Cyanoramphus) 
were reported as being very numerous at the 
same time. At least four such outbreaks are 
known to have occurred between 1872 and the 
last in 1888 (Watson, 1956). It is tempting to 
explain the cessation of these outbreaks as a 
result of the introduction of mustelids at about 
this time in an attempt to check the spread of the 
introduced rabbit. In the twelve years from 1884 
to 1895 over 6,000 stoats and weasels were 
liberated, some of which spread rapidly into the 
forests. 

On Raoul Island in the Kermadec Group, 
600 miles north of New Zealand, norvegicus 
has virtually replaced exulans. In a recent 
publication (Watson, 1956), I assumed that 
norvegicus arrived on the island during the last 
war, but evidence has recently come to light 
showing that this species came in a ship wrecked 
there in 1921 ; exulans was still numerous there 
down to 1944 but has not been found since. 
It is of some interest that it should have taken as 
long as twenty years for the one species to 
replace the other on an area of about eleven 
square miles. To-day in New Zealand, exulans 
is numerous only on outlying islands where 



neither of the other two rat species occurs. On 
the two main islands it is extremely uncommon 
and in recent years it has been found only in the 
forests of the south-west. There is also an 
interesting record of one being caught in the same 
trap line as rattus on Stewart Island where 
norvegicus also occurs. 

Rattus is present throughout the country: 
in towns where it is an important pest economi- 
cally, and in the indigenous forests where it feeds 
on fruits, seeds and insects. The three color 
forms of this species, usually given the subspe- 
cific names: rattus, with black back and grey 
belly; frugivorus with brown back and creamy- 
white belly; and alexandrinus, with brown back 
and grey belly; all occur in New Zealand. It 
is probably better outside Asia to consider them 
as forms of a polymorphic species rather than as 
separate subspecies. The grey-bellied alexandri- 
nus is rare except on Stewart Island in the south, 
and in the forests on the west of the South Island. 
The pale-bellied frugivorus type is the commonest 
both in towns and forests. The black rattus 
type forms about 20 per cent of the population. 

Norvegicus is widely distributed throughout 
the country. As is to be expected, the largest 
populations occur in towns, particularly around 
rubbish dumps and similar places; but this species 
is also found well away from towns, around farm 
buildings in the country and even along creeks 
on the edge of forested country far from human 
habitation. Accounts of this species swarming 
in the southern forests seventy five years ago are 
possibly due to confusion with exulans. Norve- 
gicus is the only species present on the subantarc- 
tic Campbell Island. 

A survey of rat infestations was carried out by 
the writer in industrial premises in the town of 
Christchurch five years ago. Both rattus and 
norvegicus were present; neither could be said to 
be dominant though rattus tended to be econo- 
mically the more important as it was the com- 
moner occupant of food stores and buildings, 
particularly above ground level. The infestations 
of neither species were on the whole serious and 
many environments potentially suitable for rats 

15 



PROCEEDINGS OF THE NINTH PACIFIC SCIENCE CONGRESS 



were not occupied, and this in the absence of any 
very active control measures. 

Christchurch is similar both climatically and 
structurally to many English towns where to-day 
norvegicus is the only species present. The 
problem arises : why, if norvegicus has ousted 
rattus in England, it has not done so in the New 
Zealand urban environment also? It is not a 
matter of time; both species have now been in 
New Zealand for well over 100 years. But in 
less time than this, rattus had almost disappeared 
in England following the introduction of norve- 
gicus (Barrett-Hamilton, 1912), though in the 
United States norvegicus is still spreading at the 
expense of rattus (Ecke, 1 954). Control measures 
in New Zealand may have been biasing the situa- 
tion in favor of rattus since at the time of the 
survey the proprietory brands of poison bait most 
commonly available on the market contained 
either "antu" or red squill, both relatively ineffec- 
tive against this species. At least one instance was 
discovered where an infestation of norvegicus 
was cleared out, only to be replaced by one of 
rattus. The intensity of control, however, was 
insufficient by itself to have accounted for the 
general situation. 

One big differences between New Zealand and 
England is that in New Zealand, rattus is also an 
inhabitant of the forests which it appears not to 
have been in England, possibly because this 
ecological niche was already filled by other 
woodland rodents. For competition between 
two species to be a reality, there must be an in- 
sufficiency of a common necessity such as food 
or cover to meet their joint requirements. The 
impression gained at the time of the survey in 
Christchurch was that the populations of neither 
species were being limited by shortage of food or 
suitable habitat, so that in effect there was prob- 
ably very little competition between them. 
Without competition there was no obvious reason 
why the two species should not both have been 
present in the same town. Presumably in the 
past there would have been periods when both 
species were competing, and at such times 
norvegicus would have spread at the expense of 
rattus. But the existence of the rural rattus 
population would have provided a source for 
the replenishment of the urban population 
when the intensity of interspecific competition 
diminished. In any case, there is a tendency for 
rattus to invade houses in autumn with the onset 
of colder weather. 

Exulans is reported from several Pacific Islands 
as having been driven out or its numbers greatly 
diminished as a result of the introduction of one 

16 



or other of these two rat species. Most of these 
reports should probably be treated with some 
caution, particularly as exulans (hawaiiensis) 
on the Hawaiian Islands was generally considered 
prior to its rediscovery in 1917 to have been 
replaced by the other two species (Stone, 1917). 
Two relatively recent first-hand accounts of 
biological surveys, on Raroia atoll in the Tua- 
motus (Morrison, 1954), and in the Marquesas 
(Mumford, 1942), report exulans being replaced 
by rattus. On the other hand, population 
studies that have been carried out on Guam 
(Baker, 1946), New Caledonia (Nicholson and 
Warner, 1953), and Hawaii (Spencer and Davis, 
1950) have shown exulans living together with 
rattus; in the last two places norvegicus is also 
present. 

The problem of interspecific competition 
among rats is extremely complex. All three 
species have quite distinct ecological require- 
ment, which in South East Asia keeps one sepa- 
rate and enables the other two to co-exist in close 
proximity. However, the segregating mechanism 
preventing competition, breaks down under 
different conditions. In the Pacific there is a 
multiplicity of islands with various habitats, and 
different combinations of the three species of 
rats. Moreover, on some, rattus and norvegicus 
are only comparatively recent arrivals as a result 
of the last war. Here, therefore, is a unique 
opportunity for the collection of information to 
elucidate this problem. 

REFERENCES 

Baker, R.H., 1946, A study of rodent populations 

on Guam. Ecol. Mongr. 16: 393. 
Barrett-Hamilton, G.E.H., 1912, "A history of 

British Mammals" vol. 2: 583. 
Ecke, D.H., 1954, An invasion of Norway rats 

in Southwest Georgia. /. Mammal. 

35: 521. 
Morrison, J.P.E., 1954, Animal ecology of Raroia 

Atoll. Atoll Res. Bull. 34. 
Mumford, E.P., 1942, Native rats and the plague 

in the Pacific. Amer. Set. 30: 213. 
Nicholson, A.J., Warner, D.W., 1953, The rodents 

of New Caledonia. /. Mammal. 34: 168. 
Spencer, H.J., Davis, D.E., 1950, Movements and 

survival of rats in Hawaii. /. Mammal. 

31: 154. 
Stone, W., 1917, The Hawaiian rat. Occ. Pap. 

JB.P. Bishop Mus. 3: 251. 
Watson, J.S., 1956, The present distribution of 

Rattus exulans in New Zealand. N.Z.J. 

Set. Tech. B. 37: 560. 



VOLUME 19 



ZOOLOGY 



DISCUSSION 



H.J. COOLIDGE: An interesting paper; we should 
hear more later on the concurrence of Rattus rattus and 
R. exulans. I am surprised that Watson puts the date 1921 
on the introduction of R. norvegicus to New Zealand. 

J.L. HARRISON: This date refers to the introduction 
to one specific island. 

j.j. CHRISTIAN: Competition between R. norvegicus 
and R. rattus, or between any other pair of species not 
necessarily competitive for food, harborage or other eco- 
logical features, may be competitive on a social basis, 



i.e., larger and more aggressive species will drive off a less 
aggressive species as shown by the work of Barnett with 
the species cited here. 

M.H. SACHET: Is there evidence for extermination of 
R. exulans from Funafuti? 

J.L. HARRISON: I cite Watson's reference to Waite, 
1897, Mammals, Reptiles and Fishes of Funafuti. 

M.H. SACHET: I suggest a misinterpretation of this 
paper by Watson, because R. exulans was taken on that 
survey. 



17 



PROCEEDINGS OF THE NINTH PACIFIC SCIENCE CONGRESS 

^PACIFIC ISLAND RAT ECOLOGY PROJECT 



ROBERT L. STRECKER 

Pacific Science Board, National Research Council, Washington, D.C., U.S.A. 



(Abstract) 



The Pacific Science Board of the National 
Academy of Sciences National Research Coun- 
cil has sponsored a three year program of basic 
research on rats as they fit into the environment 
of the tropical Pacific islands. The study is 
centered on Ponape, E. Caroline Islands, U.S. 
Trust Territory of the Pacific, with work being 
carried on in several areas of the Trust Territory. 

The field program began in 1955 and will 



continue until 1958. This report describes the 
organization, procedures, and general findings of 
the research to date, including information on 
species present, geographic distribution, repro- 
duction, sex ratios, parasites, predation, home 
range, food habits, swimming ability and general 
behavior. Detaileddata are not yet fully avail- 
able since the project is still in progress. 



DISCUSSION 



H.E. MCCLURE: Is the short-eared owl an introduced 
species on Ponape? 

R.L. STRECKER: Not as far as we know. 

H.J. COOLIDGE: It is an indigenous species. Would 
metal bands on coconut trees be of use in keeping out rats 
on Ponape? 

R.L. STRECKER: Yes, in groves planted in an orderly 
manner, and if bands are attached properly to the trees. 
Bands do not work on cacao, as they eventually kill the 
tree by girdling. 

R.L. STRECKER: 1 have not seen this employed and 
doubt if it would work. 

B. GROSS: On Tahiti metal bands are credited with 
increasing copra crop 30 to 40%. 



A.G. SEARLE: Does Taenia taeniaeformis also occur 
in R. exulansl 

R.L. STRECKER: Yes. 

J.L. HARRISON: Lungworm and other parasite burdens 
probably contribute to rat mortality in live traps in times 
of environmental stress. 

A.R. MEAD : On Saipan, Evders and J found moribund 
rats. Have you found them? 

R.L. STRECKER: No. 

H.J. COOLIDGE: Was there any interference from 
African snails in trapping? 

R.L. STRECKER: Not especially. Sometimes snails, 
toads, and rain spring traps. In the Marshalls hermit 
crabs were a great interference. 

J.L. HARRISON: Termites make it impossible to em- 
ploy wooden traps in Malaya. 



18 



VOLUME 19 



ZOOLOGY 



ECOLOGY OF THE FORMS OF RATTUS RATTUS 
IN THE MALAY PENINSULA 

J.L. HARRISON 

Zoologist, Institute for Medical Research, Kuala Lumpur, Federation of Malaya. 



Outside South-east Asia there is a growing 
realisation that although the house-dwelling 
Rattus rattus may sometimes be black, and some- 
times be brown, these color forms are but strains 
in a continuously interbreeding population of 
house-rats. The names Rattus rattus rattus 
for the black form and Rattus rattus alexandrinus 
for the brown form have little to recommend 
them, for the black rat is probably no more than 
an example of "Industrial Melanism" now so well 
described in British Moths (e.g., Ford 1945). 

The distinction between the black and the 
brown strains has, however, obscured a differ- 
ence which I consider to be more fundamental 
that between the "dull bellied" and the "white 
bellied" forms. In the Oriental Zoogeographical 
region, where the species must have originated, 
there are many named forms of rats which are 
commonly regarded as being forms of a single 
polymorphic species Rattus rattus. Various 
attempts have been made to assemble these into 
series, with varying success, and to over-simplify 
these ideas we may quote Ellerman (1947) who 
says, of Rattus rattus: "In this species there are 
two main types, one of which is dull bellied and 
mainly parasitic, and the other of which is white 
bellied and wild. Both types may occur to- 
gether." With that statement I have no quarrel, 
so long as "wild" is not taken to imply "a native 
forest form". 

Let us consider the state of affairs in Malaya. 
Here among seventeen species of the genus 
Rattus we have three, R. jalorensis, R. argentiven- 
ter, and R. diardi, which are commonly regarded 
as forms or subspecies of Rattus rattus. R. jalo- 
rensis is a white-bellied rat of woodland; argenti- 
venter is a grey-bellied rat of grassland, including 
rice fields ; diardi is a dull-bellied house rat. Their 
habitat has been summarized by Harrison (1957). 

Primitively the Malay Peninsula is forested, and 
two thirds of the Federation of Malaya is still 
covered with substantially undisturbed forest. 
After ten years experience in collecting rats there, 
I have no hesitation in saying that R. jalorensis 
does not occur in primary forest and is not one of 
the eleven species which can fairly be regarded 
as native to Malaya. Its habitat is typically the 



scrub which results when the forest is felled (and 
the native fauna driven away), and the land is 
neglected. It also occurs in the "imitation" 
forest made by man when he plants rubber, oil 
palm, coconut palm, or thatch palm trees. 

In large areas of Malaya the primitive swamp 
forest has been felled, and the cleared land used 
for growing rice. In other parts, land cleared but 
not cultivated has been seized by the cosmopoli- 
tan grass Imperata cylindrica which is perpetuated 
by burning. It is these two forms of grassland, 
ricefields and Imperata-grass, that Rattus argen- 
tiventer inhabits and it will be noted that both 
habitats are man-made. 

In the region of Kuala Lumpur, Rattus diardi 
is essentially a house rat. It is the principal rat 
in houses, forming 72% of some 10,000 animals 
trapped by municipal rat-trappers in Kuala 
Lumpur (the only other rat being R. exulans 
2%); it is rarely found out-side of houses, and is 
never found far from houses (rarely more than 
50 metres from a house). 

This is the state of affairs in the part of Malaya 
near Kuala Lumpur. We have three quite dis- 
trict members of this Rattus rattus complex. 
Each inhabits an ecologically distinct habitat, 
and each of these habitats is man-made. There 
is no sign of any member of the complex in pri- 
mary forest. Furthermore, the three rats are 
distinct, morphologically, and appear to breed 
true. There is no sign of overlap or intermediates. 
In other words, in Malaya these three rats behave 
as good species. 

There is nothing new in what I have been 
describing. A very similar state of affairs was 
described for Java nearly thirty years ago by 
Kopstein (1931) while Sodhy (1941) attemps to 
arrange all of the forms of Rattus rattus known 
to him into three "ecological sections" of which 
the three forms mentioned above are the Malayan 
representatives. He includes a fourth, the 
"Lugens-section" for a number of forms for 
which he has no ecological data, and which, 
being entirely unknown to me, I propose to 
omit from consideration for the time being. 
Generally speaking we can say that this three- 
fold division is recognisable throughout Malaysia, 

19 



PROCEEDINGS OF THE NINTH PACIFIC SCIENCE CONGRESS 



and that at least two of the divisions (those corres- 
ponding to the Malayan white-bellied jalorensis, 
and the dull-bellied diardi) are to be recognised 
in most of the Indian, and Indo-chinese regions. 
The Philippines appear to possess argentiventer 
(Clark, in press) I am not clear as to the relative 
status of the many forms named, but the threefold 
division is recognisable (Clark, personal com- 
munication). 

The difficulty arises when we try to express these 
ideas in conventional taxonomic terms. One 
school of thought would wish to regard the three 
sections as "ecological subspecies" of Rattus 
rattus, another would wish to regard all the local 
forms as subspecies, and to assemble the sub- 
species into "ecological sections." Sody (1941), 
who tries the latter course, remarks that "in 
some regions these groups can, in other regions 
cannot, be distinguished as regards morphology. 
In the south eastern of the Lesser Sunda Islands 
the animals of thet hree Java sections are hardly 
distinguishable . . . East of Celebes the sections 
merge almost completely. Animals from those 
regions largely agree in colour and in number of 
mammal with the western house rats . . . These 
rats occur in houses but apparently they are 
the common field rats at the same time." 

Similar difficulties are found when we go to the 
north and west. In Southern China (e.g., Hong 
Kong) there is a white-bellied field rat (sladeni) 
and a dull bellied house-rat (flavipectus) (Romer 
in lift.). The latter appears indistinguishable 
from diardi; there is no sign of argentiventer. 
In Burma, however, there is no dull-bellied rat 
at all. The Rattus rattus complex is represented 
by a white bellied rat (khyensis, etc.) which is 
typically found in such places as bamboo clumps, 
and is secondarily a house-rat (Harrison and 
Woodville, 1948). Otherwise the house-rat 
appears to be Rattus exulans, with sometimes 
Bandicoot rats burrowing in the floor. Hinton 
(1918), in describing the results of the Indian 
mammal survey, states that only white-bellied 
forms were obtained from Assam, Burma, and 
Tenasserim, while Audy et al. (1953) and Roonwal 
(1949) mention only the white bellied R. bullocki 
(probably a synonym of brunneusculus), even 
from houses and villages, near Impal in Manipur. 

In India the picture presented by Hinton (1918) 
is of a wealth of local forms of the white bellied 
type, typically from open countryside, and an 
exceedingly variable population of dark-bellied 
forms associated with houses. Dark-bellied 
forms only were found from Kutch, eastward 
to Gwalior, southward through Bombay to Bel- 

20 



lary, while dark and white-bellied forms occurred 
together in Kathiawar (Saurashtra), the old Cen- 
tral Provinces (Madhya Pradesh) Mysore, and 
parts of the Punjab at the foot of the Himalayas. 
From Ceylon, Travancore, up the east coast to 
Orissa, and Bengal only white bellied forms 
occurred. 

Finally, in the Mediterranean region the com- 
mon form is a dull bellied house-rat but a white 
bellied form (frugivorus) is to be found living 
"wild" in trees, where it is a pest in plantations 
of carob and olive trees for example. 

The difficulty is, therefore, that while in 
Malaysia we can distinguish three entities, dis- 
tinct both morphologically and ecologically, 
as we leave Malaysia we find that morphology 
and ecology no longer agree, and our classification 
breaks down. 

These difficulties arise, I think largely because 
of two assumptions which are made, perhaps 
uncpnciously, by many of the writers on this 
subject. These assumptions are (1) that the 
morphological grouping (e.g. into dull and white 
belley) and the ecological grouping (e.g., into 
house and field rat) should necessarily agree; 
and (2) that the white-bellied rat is a native 
(Chasen 1933). 

Let us consider what happens when we leave 
that part of Malaya immediately around Kuala 
Lumpur. First, let us go south, to Singapore. 
Here, as my colleagues from the University of 
Malaya have explained (Dhaliwal and Searle 
in press), Rattus argentiventer does not occur. 
R. jalorensis has been recorded but it is rare. 
R. diardi, however, is most abundant, and lives 
in all three of the habitats which, near Kuala 
Lumpur, have their own characteristic form. 
Thus diardi lives in houses, in grassland without 
contact with houses, and in scrub and secondary 
woodland. Also we have to consider another rat, 
R. annandalei, a white-bellied rat obviously 
closely related to jalorensis, which, near Kuala 
Lumpur, is very rare and appears to be confined 
to forest edge. In Singapore it is the common 
inhabitatant of secondary forest. 

Now what happens if we go east, from Kuala 
Lumpur across the mountains to the central plains 
and the east coast? This is a region with few 
inhabitants, of small villages and few even moder- 
ately sized towns. I must speak with caution 
because my knowledge is not as extensive as I 
would wish, but it appears that diardi is hard to 
find. The house rat of villages is either jalorensis 
or the little R. exulans (which is also a rat of 
grassland and scrub). Even in the town of Kuantan 



VOLUME 19 



ZOOLOGY 



(23,000 inhabitants) a recent collection produced 
only one specimen of diardi, although R. exulans, 
R. norvegicus, and Mus musculus were caught. 
It would appear that R. diardi is but little estab- 
lished as a house rat on the East Coast, and that 
R. jalorensis functions effectively in its place. 
This leads us to read, in a new light, a remark by 
Chasen (1933) who says, of the collection of 
skins of diardi in the Raffles Museum, Singapore, 
"owing no doubt to the luck of collecting, the 
collections examined contained no specimens 
from Peninsular Siam, Kedah, Kelantan, Treng- 
ganu, Negri Sembilan, and Malacca". That is 
to say, none from the whole of the East coast of 
Malaya down to within about 100 miles of 
Singapore. It may well have been the luck of 
collecting, but it may equally be an indication 
that R. diardi has only recently established itself 
on the East side of the Peninsula. 

Let us finally travel to the islands in the Straits 
of Malacca. There are a fairly large number, 
many of them covered with dense forest which 
at first sight appears to be typical primary forest. 
I have personal knowledge only of three groups, 
the Sembilan Islands, near the coast of Malaya, 
Jarak, in about the middle of the Straits, and 
Berhala close to Sumatra. As has been explained 
by Wyatt-Smith (1953), the forest on the islands 
of these three groups is unlike that of the main- 
land and resembles rather that of an oceanic 
island. It is suggested that at some time in the 
past these island have been entirely denuded of 
life, perhaps by a fall of volcanic ash, and that 
the present fauna and flora is the result of chance 
introduction. The rodent fauna agrees with this 
idea. None of the mainland forest species occur, 
and the only rat is, in each case, a member of the 
Rattus rattus complex. On the Sembilans, close 
to Malaya, and on Berhala, close to Sumatra, 
the rat is very close to R. jalorensis although the 
Sembilan form has been named as a separate 
subspecies (Robinson and Kloss, 1911). On Jarak, 
right in the middle of the straits, and not normally 
visited by fisherman, the rat is distinct and appears 
to me to be more nearly allied to R. diardi than 
to R. jalorensis, (Harrison 1950). 

Here, then, are all of the anomalies which we 
find outside Malaysia presented within Malaya. 
R. diardi, a typical dull-bellied house rat, may 
be found in grassland and scrub on Singapore 
Island, and in forest on Jarak. Jalorensis, a 
typically "white-bellied and wild" type of rat, 
is never a truly wild (i.e., forest) rat in the Penin- 
sula, and is a common house-rat on the East side, 



but in the island of the Malacca Straits it is a 
forest rat. 

We can explain these anomalies in Malaya by 
assuming that the three members of the Rattus 
rattus group, jalorensis, argentiventer and diardi 
are three distinct species, each commensal, which 
have each separately been introduced into 
Malaya. Jalorensis would have been introduced 
first as a house rat with peoples moving down, 
coastwise from the north. It found the native 
annandalei inhabiting forest edge and replaced 
it almost everywhere except in the far south. 
Argentiventer was introduced with rice perhaps 
from Java. Finally diardi is a recent introduction 
from Southern India, introduced as a house-rat 
of towns to the newly settled island of Singapore, 
which jalorensis had not, at that time, reached. 
Thence it spread with good communications up 
the West coast, and completely replaced jalorensis 
as a house rat, but failed to compete successfully 
with the latter in scrub and plantations, so that 
jalorensis, originally a house-rat, now appears 
to be only a rat of scrub. The Islands near the 
shore were colonised early by jalorensis carried 
by fisherman, at a time when it was the only 
house rat, but the more remote Jarak was col- 
onised by a dull-bellied rat carried on sea-going 
ships. 

I can perhaps best sum up by giving an Hy- 
pothesis, and 1 must emphasize that it is only a 
hypothesis, to account for the three of Rattus 
rattus which we have been considering. 

I suggest that the original form was a white- 
bellied, semi-arboreal rat living somewhere in 
India or Burma, perhaps in the Ganges plain. 
This rat came into contact with man in an early 
agricultural culture, and became adapted to the 
habitat provided by forest clearing, scrub, and 
flimsy houses of bamboo and thatch, perhaps built 
on stilts, as are so many houses in South East 
Asia. Spreading by man's unconscious agency 
this form rapidly colonized the cultivated areas 
and its fringing scrub throughout India and 
Burma, up into China, down into Malaysia, and 
westwards, through Persia into the Mediter- 
ranean. At that time there would have been an 
almost continuous belt of cultivation and scrub 
crossing the present desert areas. Westward 
and Northward spread would be rapid into well- 
settled areas, but spread to the South-east would 
be slow, into areas then largely covered with 
forests with very few scattered clearings. 

This white-bellied, semi-arboreal form devel- 
oped two adaptions to life in the open treeless 
areas, where animals have perforce to live in 

21 



PROCEEDINGS OF THE NINTH PACIFIC SCIENCE CONGRESS 



burrows, instead of tree-nests, and typically have 
a dull coloured belly. Although dull bellies are 
associated with house-rats they are also to be 
found in those murids which live in the open 
grassland rather than in woodland. 

Thus in the British Isles the grass-eating Voles 
(Microtinae) tend to be dull bellied in contrast 
to the so-called field mice (Apodemus) which in 
fact live in woods and hedgerows and are pale 
bellied. Within the genus Apodemus the species 
A. agrarius, which tends to live in the open is 
somewhat darker-bellied than A. sylvaticus 
which tends to live in woodland (Allen 1940). 

Of the two dull-bellied forms in the Rattus 
rattus group one was adapted to tropical grass- 



land and ricefields, and has spread over Malay- 
sia as argentiventer. The other adaption was 
probably to steppe country in South western Asia, 
and this secondarily became adapted to life 
wholly in the substantial houses which, by this 
time, were being built from Egypt to Mohenjo 
Daro. This was the present dull-bellied house 
rat. 

With the dessication of South western Asia, 
the white-bellied form tended to disappear leaving 
the present discontinuous distribution shown 
in the figure and the dark-bellied form became the 
only form to be associated with man there. It 
spread westward into Europe (where a wholly 
black form was developed) and thence by 




DULL BELLIED WHITE SVg P 

Fig. l. Distribution of the three "forms" of the Rattus rattus group in the area considered. 



22 



VOLUME 19 



ZOOLOGY 



European shipping to America, South Africa, and 
more recently every seaport in the world. East- 
ward it spread into India where it is still spreading 
over the central parts. It spread down the West 
Coast and thence, by shipping, across to Malay- 
sia, where as the above records show, it is still 
spreading. From Malaysia it spread North up to 
the Eastern coast to Southern China. To the 
Eastward it overtook and replaced the still 
spreading white-bellied form at the Celebes, 
replaced it as the house-rat, which is the form 
most readily spread by man, and then spread to 
New Guinea and the adjacent islands where it 
is present as a variable, apparently "local" 
from. Australia, on the other hand, would have 
been colonized by the form from Europe. 

SUMMARY 

1. In Malaysia rats of the Rattus rattus group 
can be divided into three kinds, a dull-bellied 
house-rat (diardi), a silver-bellied grassland and 
ricefield rat (argentiventer) and a white-bellied 
woodland rat (jalorensis). No member of the 
group is native to forest. 

2. Outside Malaysia this threefold morpholo- 
gical and ecological classification breaks down. 
It is not usually possible to distinguish three forms, 
and the members of any one morphological type 
may appear in the "wrong" habitat. 

3. Detailed studies in Malaya suggest a solu- 
tion. Here the threefold division is found near 
Kuala Lumpur on the West Coast, but elsewhere 
one or more of the members may be missing, 
and the other members of the group occupy the 
habitat normally associated with it. 

4. It is suggested that the three forms are best 
regarded as three species of Rattus, each of which 
is a commensal with man, which have been 
separately introduced into Malaysia and which 
have not yet wholly occupied the area. 

REFERENCES 

Allen, G.M., 1940, The mammals of China and 
Mongolia. Natural History of Central 
Asia XI pt. 2. American Museum of 
Natural History, New York. 

Audy, J.R., Thomas, H.M. and Harrison, J.L., 
1953, A collection of trombiculid mites 
from Manipur and Lower Burma 1945- 
56. J. zool Soc. India 5:20-40. 



Chasen, F.N., 1933, on the forms of Rattus rattus 
occurring on the mainland of the 
Malay Peninsula. Bull Reffles Mus. 
8:5-24. 

Clark, R.J., (in press). Observations on the Rat 
Infestation of Cotabato, the Philippines. 
Proc. 9th. Pacif. Sci. Congr. (This publi- 
cation). 

Dhaliwal, S.S. and Searle A.G., (in press). The 
Rats of Singapore Island. Proc. 9th. 
Pacif. Sci. Congr. (This publication). 

Ellerman, J.R., 1947, Notes on some Asiatic 
Rodents in the British Museum. Proc. 
zool. Soc. Lond., 177:259-271. 

Ford, E.B., 1945, Butterflies. New Naturalist 
series ; Collins, London. 

Harrison, J.L., 1950, "The Animals", in Audy, 
J.R., Harrison, J.L., and Wyatt-Smith, 
J. (1950)., A survey of Jarak Island, 
Straits of Malacca. Bull. Raffles, mus. 
23:230-261. 

Harrison, J.L., 1957, Habitat of some Malayan 
Rats. Proc. zool. Soc. Lond. 128:1-21. 

Hinton, M.A.C., 1918, Scientific results from the 
mammal survey No. XVIII-Report on 
the houserats of India, Burma, and 
Ceylon. J. Bombay nat. Hist. Soc. 
26:59-88, 384-416, 616-725, 906-918. 

Kopstein, F., 1931, Die Okologie der javanischen 
Ratten. Z. Morpli. Okol. Tiere 22: 
774-807. 

Romer, J.D., (in litt.) personal communication. 

Roonwal, M.L., 1949, Systematics, ecology, and 
bionomics of mammals studied in 
connexion with tsutsugamushi disease 
in the Assam-Burma war theate during 
1945. Trans. Nat. Inst. Sci. India 3: 
67-122. 

Robinson and Kloss, 1911, on six new mammals 
from the Malay Peninsula and adjacent 
islands./. FMS. Mus. 4:169-174 (Mus. 
rattus rumpia). 

Sodhy, H.J.V., 1941, on a collection of Rats from 
the Indo-Malayan and Indo-Australian 
Regions (with descriptions of 43 new 
genera, species and subspecies). Treubia 
18:255-325. 

Wyatt-Smith, J., 1953, The vegeration of Jarak 
Island, Straits of Malacca. /. Ecology. 
41:207-225. 

23 



PROCEEDINGS OF THE NINTH PACIFIC SCIENCE CONGRESS 



DISCUSSION 



R.L. STRECKER: There is the puzzling situation in 
color variations of roof rats. A black phase and all inter- 
grades are found on islands investigated. 

J.L. HARRISON: I have seen no black phase rats in 
Malaya. We usually think of black phases in cold coun- 
tries, but this negates such a supposition. 

A.O. SEARLE: Does R. norvegicus spread outside port 
areas anywhere in the tropics? 

B. GROSS: Yes, if you consider Hawaii in the tropics. 
It spreads to cane fields, even up into mountains. 

J.R. AUDY commented on the parasite burden and 
diseases in rats. 

R.L. STRECKER: On Ponape Capilleria and other 
worms do occur but not as heavy burdens. Some are 
parasite-free. 

H.J. COOLIDOE: Are there any studies on the rela- 
tions between rats and crabs? 

J.L. HARRISON: Very little. 

E.H. TAYLOR: In the Philippines the rat's diet varies 
from place to place. Where they eat crabs the rat-size 
seems larger. Samplings anywhere in Malaya should take 
into consideration populations of Ptyas korras, P. mucosus, 
and Zaocys carinatus, the three rat snakes. 



J.L. HARRISON: Snakes are killed in Malaya around 
residential areas. Rattus jalorensis near gardens are about 
twice as long as those in scrub where snakes are numerous, 
suggesting destruction of snakes alters the mode of life of 
the rat. 

J.R. AUDY commented on the introduction of rats into 
Berhala, their health condition and predation. 

H.J. COOLIDGE: Are there any estimations of the cat 
population? 

J.R. AUDY: The cat population is not great, but they 
are the only predators there. 

H.J. COOLIDOE : In swimming tests, rats are sometimes 
taken by turtles and fishes. 

i MCT. COWAN: commented on the occurrence of 
rat parasites on islands, that they are introduced along 
with the host, and that changes in host diet affects host 
resistance. Health and population density go together. 

A.G. SEARLE: Differences between health and num- 
bers of rats on Berhala and Jasah may have been because 
they were at different stages of the population cycle. 



J.L. HARRISON: 
for grassland rats. 



There seems to be a five year cycle 



24 



VOLUME 19 



ZOOLOGY 



THE BIOLOGICAL BASIS OF RODENT CONTROL 

JOHN J. CHRISTIAN and DAVID E. DAVIS 

Naval Medical Research Institute, Bethesda, and the Division of Vertebrate Ecology, The Johns Hopkins School 
of Hygiene and Public Health, Baltimore, Maryland, U.S.A. 



INTRODUCTION 

The premise of this paper is that rodent control, 
to be successful, must be based on the sound 
application of biological principles in a systema- 
tic attack on a population of a given species. 
Much evidence under-scores the statement that 
the most effective way to reduce a population and 
maintain it at a reduced level is to increase intra- 
specific competition (Davis, 1949). Recent research 
has made it evident that competition, or social 
pressures, induces physiological responses which 
have a suppressive effect on the growth of 
populations. The balance of this paper will be a 
more detailed account of such a chain of events 
along with a summary of the experimental evi- 
dence for its existence. However, it should be 
born in mind that predation by man or other 
predators (in the broadest sense) has been gener- 
ally ineffective in the sustained control of popula- 
tions. In fact the usual poisoning or trapping 
campaign, unless maintained at a continuously 
very high level of intensity, usually results in an 
increased reproductive rate following the initial 
reduction in population size with a resultant 
rapid return to (or above) the original level 
(Davis, 1949, 1951; Barnett, 1952). For example, 
where populations of rats in Baltimore City were 
reduced by trapping to 50 to 90% of their initial 
levels, there was an initial rate of recovery of 
4% of the maximum per month which later 
slowed to 2% a month as the population ap- 
proached the initial level (Emlen, Stokes, Winsor, 
1948). The data of these authors clearly show a 
relationship between population density and the 
rate of recovery following decimation of the 
population. Poisoning campaigns usually are 
unsuccessful even with sustained effort, due to 
the development of bait shyness on the part of 
the rats (Barnett, 1952). 

We clearly recognize that there will be consid- 
erable variation in the details of methodology 
with different species and different environments, 
and that it will be necessary to know the life 
history of an animal in a particular environment 
in order to know the best way to increase com- 
petition effectively. For example, rat control 
in urban areas can be achieved by general sani- 



tation which increases competition by reducing 
the available supplies of food and harborage. 
However, as Barnett points out (1952), sanitation 
of this sort is not generally practicable for rural 
populations. Hence other methods of increasing 
competition must be sought. Nevertheless 
the general principle will remain the same: 
achieving population control by increasing 
competition even though the means may vary. 

The limited information available in 1953 on 
the effects of competition on population growth 
permitted only one page to be devoted to this 
subject in a 22-page review of the characteristics 
of rat populations (Davis, 1953). Nevertheless 
it had been apparent for some time that competi- 
tion was an important factor in the regulation of 
rat populations (Eaton and Stirrett, 1928; Cal- 
houn, 1949; Davis, 1949, 1951). It had already 
been shown that reducing the size of a rat 
population resulted in increased reproduction 
and growth in the survivors (Davis, 1949). A 
mechanism involving physiological responses to 
population density capable of explaining how 
competition exerted its effects was hypothesized 
in 1950 (Christian). Experiments have since 
established the existence of such a mechanism as 
well as having emphasized greatly the importance 
of intraspecific competition in the regulation and 
control of rodent populations. We now believe 
that competition is the primary factor regulating 
and controlling the growth and decline of rodent 
populations and that nutritional or environmental 
deficiencies affect populations mainly by increas- 
ing competition as had been suggested by Davis 
(1949) and later developed in greater detail 
(Christian 1957). 

POPULATION CHARACTERISTICS 
AND FORCES 

No attempt to describe the various characteris- 
tics of rat populations will be made here, as the 
subject has been thoroughly reviewed elsewhere 
(Davis, 1953). The same applies to the forces 
affecting population growth, namely: mortality, 
reproduction and movements. Suffice it to say 
that any factor operating to decrease reproduc- 
tion and/or increase mortality will reduce the 

25 



PROCEEDINGS OF THE NINTH PACIFIC SCIENCE CONGRESS 



size of the population, and conversely, any factor 
increasing reproduction and/or decreasing mor- 
tality will produce an increase in population size. 
Immigration in a sense may be considered to 
parallel increased reproduction and emmigration 
increased mortality. The logical way to control 
rodent populations is therefore to find a method 
of increasing mortality and decreasing repro- 
duction by utilizing factors in the life-equation 
of the given animals. We shall see that social 
competition, varying in intensity with the size 
of a population, produces physiological responses 
which result in precisely these effects on reproduc- 
tion and mortality. Therefore competition, as 
part of sociopsychological-physiological feed-back 
system, may be used as a means of regulating 
and limiting population growth. 

THE THEORY AND THE EXPERIMENTAL 
EVIDENCE 

It is now well established that a wide variety 
of noxious stimuli produce a condition of "stress" 
in animals subjected to these stimuli (Selye, 1946). 
The "stress* manifests itself by eliciting increased 
activity of the anterior pituitary-adrenocortical 
system which is measurable by increases in 
adrenal weight and increased production of 
adrenocortical steroids (Sayers and Sayers, 1949; 
Nelson, 1956). The hypothalamus is probably an 
integral link between the higher centers of the 
central nervous system and the anterior pituitary 
(Harris, 1956). Our theory proposed that with in- 
creasing population size there would be increasing 
social pressures (competition) which would act as 
stimuli to the production of stress in the individ- 
uals of a population. The stress would be in 
some proportional relationship to population 
density and would therefore elicit a proportional 
response in the pituitary-adrenocortical system. 
It was also postulated that reproduction, growth 
and resistance to disease would decline in pro- 
portion to the increase in adrenocortical activity 
and therefore to population density (Christian, 
1950, 1957). Presumably the sociopsychological 
pressures would act through the higher brain 
centers to stimulate the appropriate center in the 
hypothalamus which in turn would stimulate 
increased adrenocorticotrophin production and 
inhibit the production of growth and gonado- 
trophic hormones. It was therefore necessary 
to demonstrate a positive relationship between 
population density and the activity and size of the 
adrenal cortex and a negative relationship 
between population density and reproductive 
function. In order to establish that competition 

26 



was purely social and always present and active 
in relation to density it was absolutely essential 
to eliminate competition for food, water and 
nest space (and harborage when appropriate). 
Therefore all experimental populations were 
liberally provided with food and water from 
several sources at all times and, where pertinent, 
nest space and harborage were provided in 
excess of their usage. The adrenal glands were 
weighed routinely and enough examined histolo- 
gically to establish that weight changes were due 
primarily to changes in the amount of cortical 
tissue, specifically of the zona fasciculata. The 
weights of the thymus and preputial glands were 
taken for both sexes and the weights of the 
seminal vesicles and testes were also obtained for 
the males. The ovaries and uteri of all females 
were examined for pertinent reproductive data. 
(Christian, 1955 a, b, 1956). 

Prior to initiating or during the course of our 
program there were a number of experiments 
conducted with mice in the laboratory which 
indicated a relationship between reproductive 
performance and population density (Crew and 
Mirskaia, 1931 ; Retzlaff, 1938; Andervont, 1944). 
There also have been several experiments suggest- 
ing that competitive social behaviour resulted in 
stress with a correspondingly increased adreno- 
cortical activity. Barnett showed that the subor- 
dinate male rats in a group had larger adrenals 
with presumably a greater production of adreno- 
cortical steroids than their dominan brethren 
(Barnett, 1955). He further noted that mortality 
in these animals was probably not related to 
fighting but rather to exhaustion or "shock", 
confirming our observations for mice (Christian, 
1954). Clarke (1952) demonstrated an increase 
in adrenal weight, thymic involution, and 
splenic hypertrophy associated with placing 
alien voles in with a pair indigenous to the cage. 
Finally, Bullough showed that the adrenal cor- 
tices in grouped mice were larger than in isolated 
controls (1952). It is noteworthy, however, that 
none of these experiments were designed to show 
a relationship between progressive changes in 
population density and the adrenal cortex, a 
point essential to the theory which assigns the 
fundamental responsibility of controlling the 
growth of mammalian populations to density- 
dependent physiological responses. Our experi- 
ments were designed specifically to demonstrate 
such a relationship. 

We first were able to show that when previously 
isolated male mice were placed together the 
weights of their adrenal glands a week later were 



related to population density, apparently to the 
logarithm 10 of the population size (Christian, 
1955 a, b). It appeared that the weights of the 
adrenals decreased from preceding levels after 
a certain level of population was reached, but 
this anomaly was later explained by demonstrat- 
ing a marked depletion of the intracellular cortical 
lipids even though the number of cells had 
actually increased (Christian, Unpbl.). Parallel- 
ing the progressive increase in adrenal weight 
with progressive increases in population size, 
there was an inverse relationship between the 
weights and activity of the reproductive organs. 
These same relationships were shown to exist in 
freely growing populations of wild house mice 
(Christian, 1956). The latter experiments addi- 
tionally demonstrated that female mice were 
affected similarly to the males, but to a quantita- 
tively smaller extent. Birthrates and infant survi- 
val rates declined linearly with the logarithm 10 
of the increasing population size. The younger 
animals (and presumably subordinate) were more 
severely affected than the larger and older ani- 
mals. There was a marked delay with respect to 
body weight in the attainment of reproductive 
maturity, as was shown by the development of 
the reproductive organs and the onset of sperma- 
togenesis in males and pregnancy in the females. 
The effects on reproduction and the adrenal 
glands were probably greater than indicated with 
respect to chronological age as there was prob- 
ably [a suppression of growth and therefore of 
body (weight. Observations during the course of 
these experiments and at autopsy suggested that 
the deleterious direct effects of increased popula- 
tion density on the development and survival 
of the young were augmented by diminished lacta- 
tion. There were indications that lactation had 
been suppressed in the females along with the 
other reproductive functions. Chitty (1955) 
found this to be the case with voles in experi- 
mental populations, and we were able to confirm 
his results using albino house mice (Christian and 
LeMunyan, Unpbl.). We found in addition that 
the effects of diminished lactation attendant on 
crowding suppressed the growth of suckling 
infants in relation to litter size (the larger the 
litter size, the more pronounced the effect). These 
effects were also manifest for at least two genera- 
tions of progeny. Following the demonstration of 
these phenomena in the laboratory we were able 
to show that the adrenal glands of wild Norway 
rats similarly responded to changes in population 
density, in spite of an abundance of food and 
harborage (Christian and Davis, 1956, Fig. 1). 
A relationship between the prevalence of preg- 



VOLUME 19 ZOOLOGY 

nancy and population status in rats had been 
demonstrated earlier (Davis, 1953). In another 
experiment we were able to reduce adrenal weight 
appreciably by reducing the density of three 
populations of rats (Christian and Davis, 1955, 
Fig. 2). In another experiment a close relation- 
ship between population on size and adrenal 
weight was shown in a population of farm rats 
samples monthly for approximately three years 
(Christian, 1954 and Unpbl.). Finally, we 
demonstrated a relationship between adrenal 
weight and social rank in mice with the dominant 
animals having the smallest adrenals (Davis and 
Christian, 1957). 

The results of other investigators, using popula- 
tions of house mice or voles in the laboratory or 
voles in the wild, fit the theory and coincide 
with our results (Brown, 1953; Frank, 1953; 
Strecker and Emlen, 1953; Clarke, 1955; Louch, 
1956; Kalela, 1957). The combined results of 
these experiments indicate and emphasize the 
fundamental role of social competition in the 
regulation of rodent populations. Controlling 
rat populations by increasing competition (Davis, 
1951) therefore has a sound basis in biological 
fact. 

THE PRINCIPLE OF CONTROLLING 
RAT POPULATIONS 

It has been recognized for some time that 
general sanitation is an effective means of keeping 
populations of rats under control and has been a 
highly successful procedure in urban areas 
(Davis, 1951). It has been demonstrated repeat- 
edly that a reduction in the environmental capa- 
city results in a proportionately much greater 
decrease in the number of rats that one would 
have predicted, indicating that a change in the 
environment in a direction unfavorable to the 
continued support of rat population was not 
directly responsible for reducing the populations. 
Sanitation evidently acted as a means of increas- 
ing competition which was in turn directly 
responsible for the reductions in populations size. 
Sanitation of this sort is frequently difficult to 
carry out, particularly in rural areas (Barnett, 
1952), therefore it is logical to seek other means 
of increasing competition. The results of early 
experiments suggested that the introduction of 
alien rats into a population might be an effective 
means of increasing competition (Davis, 1953). 
Subsequently a series of experiments designed 
specifically to explore such effects were carried out 
(Davis and Christian, 1956). These experiments 
were conducted with increasing and stationary 

27 



PROCEEDINGS OF THE NINTH PACIFIC SCIENCE CONGRESS 



STATUS OF POPULATIONS 
LOW HIGH 



1 



NO. OF POPNS. 
120 



100 REF 



A 

T 

8 

A 
R 
Y 

7 



R 

I 

H, 

6 
12 



N 





I 
t 




* 


^ 

1 


1 

6 


s 

Hi 

9 6 



12 



J-U.O 



oaoc 



90 
80 

2 70 
^ 

ew 60 




T 



19.3% INCREASE 



F M 



F M 



FM 



F M 



F M 




/HYPOTHETICAL 
' GROWTH CURVE SHOW- 
' ING STAGES TO WHICH 
POPULATIONS WERE 
ASSIGNED. 




Fig. 1 . The relationship between the level of population and adrenal weight for populations of urban Norway rats. Each 
population was assigned to one of the five separate categories into which an hypothetical growth curve was 
divided. The means of the mean values of each population for each sex is given with its standard error. The 
number of populations in the sample for each category of population development is given. 



28 



VOLUME 19 



ZOOLOGY 



COMBINED RESULTS FOR BOTH SEXES FROM 3 POPULATIONS 
OF NORWAY RATS SHOWING REDUCTION OF ADRENAL WEIGHT 
BY REDUCING THE POPULATION 



JAN 



FEB 



MAR 



APR 



MAY 



JUNE 



JULY 



MEAN NUMBER OF J 
RATS PER POPULATION 1 



REDUCTION TRAPPING 




MEAN ADRENAL WEIGHT 
AS % OF REFERENCE 
. FOR BOTH SEXES 



140 



120 



100 



80 



60 L 

Fig. 2. The pronounced reduction in adrenal weight achieved by artificially reducing the populations. Three populations 
were used in this experiment; all were at relatively high levels initially. Thefsexes have been combined, as there 
were no appreciable differences between them on the responses of their adrenal glands. 



populations of Norway rats (Fig. 3). In each 
case a number of rats of one sex was removed 
from the population and subsequently replaced 
either by an approximately equal number of the 
same sex or by a considerably greater number 
than was removed. When the removed rats 
were only replaced, increasing populations ceased 
growing and stationary populations remained 
essentially the same (Fig. 3). However, when a 
much greater number of rats was added than were 
removed, stationary populations declined sharply 
from the original level. The latter procedure 
was not followed for increasing populations. 
These results show that the introduction of 
strange rats of either sex, even without increasing 



the population size, has profound effects on 
population growth. These effects can have been 
due to social competition only, as the populations 
were well below the capacities of the areas. The 
marked reduction of stationary populations to 
well below the environmental capacity effected 
by increasing the population with alien rats leads 
to the same conclusions. It is apparent that 
sanitation is not the only method of increasing 
competition and thereby reducing population 
size. Any means which can be found to increase 
the competition in a given population apparently 
can be used as a means of control. The above 
results serve to emphasize the self-defeating 
aspects of trapping and poisoning campaigns 

29 



PROCEEDINGS OF THE NINTH PACIFIC SCIENCE CONGRESS 



S 

QC 



140 



120 



100 



80 



60 



40 



140 



120 



100 



80 



-20 



WEEKS 
-10 



10 



60 



I 



2 POPULATIONS -LARGE NUMBER ADDED 



25 







\ 



2 POPULATIONS -SMALL NUMBERS SUBSTITUTED 




-6 



LARGE NUMERS SUBSTITUTED 
4 POPULATIONS 



-22 
22 



Fig. 3 The effects of introducing various numbers of alien rats into existing populations. The introduction of a large 
number of rats into 2 stationary populations resluted in a marked decline in the numbers of rats from the initial 
levels. Removing small numbers of rats from 2 stationary populations and substituting aliens for these had 
little effect on the populations. Substituting large numbers of alien rats for native rats in 2 rapidly increasing 
populations resulted in a cessation of the growth of the populations. 



30 



(or any other reduction of populations not 
using the intrinsic mechanisms of population 
growth) unless they are on a sustained basis with 
great intensity or by utilizing involved techniques, 
such as prebaiting (Barnett, 1952), with a high 
cost in time and effort. Even then these efforts 
may fail, as has been cited earlier. 

PRINCIPLES OF CONTROL AND 
SUMMARY 

The two primary forces affecting the growth of 
populations are mortality and reproduction. 
Increasing mortality alone, at least of the mature 
population, usually has little effect on the popula- 
tion since it stimulates increased reproduction as 
well as an increased survival rate of those individ- 
uals which do not succumb. Trapping, poison- 
ing, and disease, therefore are at best usually only 
temporary expedients in controlling rodent 
populations. It is true that with an extremely 
intensive and sustained trapping program control 
can be achieved, but the amount of effort required 
will usually be prohibitive. It is apparent there- 
fore that in order to have an effective program 
of rodent control we must use some means of 
significantly curtailing reproduction and/or infant 
survival. If such a means also increases adult 
mortality, we are that much better off. We have 
suggested that an effective means of achieving 
decreased reproduction and increased mortality 
of adult and infant rats and mice is to increase 
competition. This suggestion is supported by a 
variety of experimental evidence from the labora- 
tory and the field. At the present time we are 
unaware of any other method of successfully 
altering reproduction and particularly with such 
prolonged effects. We have also pointed out 
that the means of increasing competition will 
have to be determined for each particular situa- 
tion. This method of rodent control is based on 
our knowledge of the biology of rodent popula- 
tions and its application will still further depend 
on the utilization of biological facts and princi- 
ples. Failure to recognize and utilize these biolo- 
gical principles in the long run will result in a 
failure to achieve successful rodent control. 

REFERENCES 

Andervont, H.B., 1944, Influence of environ- 
ment on mammary cancer in mice. 
Jour. Nat 9 1 Cancer Inst., 4:579-581. 

Barnett, S.A., 1952, The biology of rat popula- 
tions. Surgo, Candlemas., 111-115. 



VOLUMEJ9 ZOOLOGY 

Barnett, S.A., 1955, Competition among wild 
rats. Nature, 175:126. 

Brown, R.Z., 1953, Social behavior, reproduction 
and population changes in the house 
mouse. Ecol. Monogrs., 23: 217-240. 

Bullough, W.S., 1952, Stress and epidermal 
mitotic activity. I. The effects of the 
adrenal hormones. /. Endocrinol, 8: 
265-274. 

Calhoun, J.B., 1949, A method of self-control 
of population growth among mammals 
living in the wild. Science, 109: 333-335. 

Chitty, D., 1955, Adverse effects of population 
density upon the viability of later gene- 
ration. In: The numbers of man 
and animals. Lover and Boyd, Edin- 
burgh, 57-67. 

Christian, J.J., 1950, The adreno-pituitary system 
and population cycles in mammals. 
Jour.Mamm., 31:247-259. 

Christian, J.J., 1954, The relation of the adrenal 
cortex to population size in rodents. 
Doctoral Dissertation, Johns Hopkins 
School of Hygience and Public Health, 
Baltimore. 

Christian, J.J., 1955a, Effect of populations size 
on the adrenal glands and reproductive 
organs of male mice in populations 
of fixed size. Am. Jour. Physiol., 
182: 292-300. 

Christian, J.J., 1955b, Effect of population size 
on the weights of the reproductive or- 
gans of white mice. Am. Jour. PhysioL, 
181:477-480. 

Christian, J.J., 1956, Adrenal and reproductive 
responses to population size in mice 
from freely growing populations. c0- 
/0&y, 37: 258-273. 

Christian, J.J., 1957, A review of the endocrine 
responses in rats and mice to increasing 
population size including delayed effects 
on offspring. AAAS Symposium on 
Ecological Research of Social Signifi- 
cance, in press. 

Christian, JJ. and D.E. Davis, 1955, Reduction 
of adrenal weight in rodents by reducing 
population size. Trans. North Am. 
Wildl. Conf., 20: 177-189. 

Christian, JJ. and D.E. Davis, 1956, The rela- 
tionship between adrenal weight and 
population status of urban Norway 
Rats. Jour. Mamm., 37: 475-486. 

31 



PROCEEDINGS OF THE NINTH PACIFIC SCIENCE CONGRESS 



Christian, J.J. and C.D. LeMunyan, Unpubl. 
Adverse effects of crowding on repro- 
duction and lactation of mice and two 
generations of progeny. 

Clarke, J.R., 1952, The effect of fighting on the 
adrenals, thymus and spleen of the vole 
(Microtus agrestis). J. Endocrinol., 
9:114-126. 

Clarke, J.R., 1955, Influence of members on 
reproduction and survival in two ex- 
perimental vole populations. Proc. 
Roy. Soc. B., 144:68-85. 

Crew, F.A. and L. Mirskaia, 1931, Effect of den- 
sity on adult mouse populations. Biol. 
General, 7:239-250. 

Davis, D.E., 1949, Intraspecific competition in 
game management. Trans. North Am. 
Wildl. Conf., 14:225-231. 

Davis, D.E., 1951, The characteristics of global 
rat populations. Am. J. Publ. Health, 
41:158-163. 

Davis, D.E., 1953, The characteristics of rat 
populations. Quart. Rev. Biol., 28: 
373-401. 

Davis, D.E. and J.J. Christian, 1956, Changes 
in Norway rat populations induced by 
introduction of rats. Jour. Wildl. Mgt., 
20:378-383. 

Davis, D.E. and J.J. Christian, 1957, Relation of 
adrenal weight to social rank in mice. 
Proc. Soc. Exp. Biol. and Med., 94: 
728-731. 

Eaton, P. and C.S. Stirrett, 1928, Reproduction 
rate in wild rats. Science, 67:555-556. 

Emlen, J.T., Jr., A.W. Stokes and C.P. Winsor, 
1946, The rate of recovery of decimated 
populations of brown rats in nature. 
Ecology, 29:133-145. 



Frank F., 1953, Untersuchungen uber den 
zusammenbruch von feldmausplagen 
(Microtus arvalis Pallas). Zool. Jahrb. 
(Systematik), 82:95-136. 

Harris, G.W., 1956, Hypothalamic control of the 
anterior lobe of the hypophysis. IN: 
Hypothalamic-hypophyseal interrela- 
tionships. Chas. C. Thomas, Spring- 
field, 111. Eds: W.S. Fields, R. Guillemin, 
C.A. Carton. 

Kalela, O., 1957, Regulation of reproduction rate 
in subarctic populations of the vole 
Clethrionomys rufocanus (Sund.). Ann. 
Acad. Sci. Fennicae; A. Biologica, 34: 
1-60. 

Louch, C.D., 1956, Adrenocortical activity in 
relation to the density and dynamics of 
three confined populations of Microtus 
pennsylvanicus. Ecology, 37:701-713. 

Nelson, D.H., 1956, Adrenocortical secretion 
and factors affecting that secretion. 
IN: 5th Annual Report on Stress, H. 
Selye and G. Heuser, pp. 169-184. 

Retzlaff, E.G., 1938, Studies on population 
physiology with the albino mouse. 
Biol. General, 14:238-265. 

Sayers, G. and M.A. Sayers, 1949, The pituitary- 
adrenal system. Ann. N. Y. Acad. Sci. 9 
50, Art., 6 -.635-645. 

Selye, H., 1946, The general adaptation syndrome 
and the diseases of adaptation. Jour, 
din. Endocrin., 6:117-230. 

Strecker, R.L. and J.T. Emlen, 1953, Regulatory 
mechanisms in house mouse popula- 
tions: the effect of limited food supply 
on a confined population. Ecology, 
34:375-385. 



The opinions or assertions contained herein are the private ones of the writer and are not to be construed as official 
or reflecting the views of the Navy Department or the naval service at large. 



DISCUSSION 



R.L. STRECKER: Actual numbers are not necessarily 
significant in terms of peak populations and their pressures. 
The important point is the amount of stress, regardless of 
size. 

j.j. CHRISTIAN: Agreed. It depends on aggressive- 
ness, physiological states, etc. 

R.L. STRECKER: What is the explanation for popula- 
tion bursts? 

j.j. CHRISTIAN: I know of no explanation as yet. 

32 



J.R. AUDY : Does it depend on the number of encoun- 
ters? 

j.j. CHRISTIAN: I do not think so. It depends on 
physiological states. 

L.E. ROZEBOOM: Would not poisoning have the same 
effect as predation in bringing down population pressures 
to the point where survivors would not experience the 
stress phenomena and so constitute a healthier population? 

j.j. CHRISTIAN: Essentially, yes. 



VOLUME 19 



ZOOLOGY 



A.O. SEARLE: Is the work done mostly on R. norve- 
gicusl 

j.j. CHRISTIAN: Mostly on Mas musculus, also other 
rats, squirrels, and now on marmots. 

J.L. HARRISON: I call attention to Twitty's work on 
caged animals, where socially inferior animals showed 
swelling and slipping of intervertebral discs. Also R. 
Jalorensis, pest of oil palms occurring in large numbers 
show smaller litter size, lower pregnancy rates and smaller 
skull length than those in the scrub where they are part of 
a larger community. 

J.L. HARRISON: What is known about stress within 
species and between species? 

j.j. CHRISTIAN: Not much is known yet. 

A.R. MEAD: What is the effect of introduction of a 
species when the indigenous species is in high stress state ? 

j.j. CHRISTIAN : When one reduces a dominant species 
experimentally, an inferior species will rise in population. 

R.L. STRECKER: Then it is a better sanitary practice 
to reduce the capacity of the habitat to support a popula- 
tion and leave the population undisturbed rather than 
reduce the population, as by trapping, at the same time. 

j.j. CHRISTIAN: This is the practice in Baltimore. 

H. TRAPIDO: How quickly do these reduced popula- 
tions recover? 

j.j. CHRISTIAN: For R. norvegicus, 6 months. In 
control practice, a population reduced 50% comes back 
rapidly. 

H. TRAPIDO: What is the definition of this stress to 
which you refer? 

j.j. CHRISTIAN: Actually we do not define what stress 
is except in terms of the animals response to it. 



R.L. STRECKER: Stress is anything which requires 
the animal to adapt. Life is all stress. When some new 
condition occurs, stress responses occur. 

H. TRAPIDO: Then why does poisoning not affect the 
population and elicit stress response? 

j.j. CHRISTIAN : Those to which the dose is not lethal 
are stronger and healthier individuals. 

J.L. HARRISON: Only individuals, not populations, 
learn about poison and avoid it. Then it is no longer a 
serious stress factor to them. 

J.R. AUDY : An apparent paradox is observed : animal 
most able to rise in great numbers seem the most high 
strung. 

j.j. CHRISTIAN: We must learn what comprises com- 
petitive situations within populations. There is much 
variability in the number of fights and other behavioral 
factors. 

J.R. AUDY: Variation in aggressiveness seems res- 
ponsible for occurrence of large numbers. 

J.L. HARRISON: The "bad tempered" animals are the 
successful ones. They cause the stress to others. 

j.j. CHRISTIAN: Dominant animals certainly are the 
most secure. 

i. MCT. COWAN: It seems that this general topic 
would lead to species adapted to "slum conditions." This 
seems to have happened in rats, mice, and man. 

j.j. CHRISTIAN: Parallel to this, with Peromyscus 
we couldn't get over 12 animals to live together, while 
Mus musculus over 100 live together. Reserpine (a tran- 
quilizer) helps raise population size of Peromyscus. 



33 



PROCEEDINGS OF THE NINTH PACIFIC SCIENCE CONGRESS 



OBSERVATIONS ON THE RAT INFESTATION OF 
COTABATO, THE PHILIPPINES 



R.L CLARK 

FAO Technical Assistance Expert on Rodent Control, Manila, Philippines.^ 



INTRODUCTION 

In the Philippines, there are more than thirty 
species of rodents. Because of their numbers and 
habits several are major pests. This paper 
concerns one species of rat which is widespread 
in the islands but which has been most intensively 
studied in the provinces of Cotabato where 
it is a serious agricultural pest. Data presented 
here were collected while the author was serving 
with the Philippine Government as a Technical 
Assistance Expert in Rodent Control for the 
Food and Agriculture Organisation of the United 
Nations from May, 1956 to May, 1957. 

Cotabato is the largest of the ten provinces 
in the island of Mindanao with an area of 2,296, 
790 hectares. In the large central lowland plain 
the main crops are rice and maize (Zea mats). 
These have suffered severely from the depreda- 
tions of rodents and, after an outbreak destroyed 
a large proportion of crops in 1953-4 and sub- 
sequently, organised rodent control was begun by 
the Philippine Government. 

PROBLEM 

In Cotabato, the species causing most concern 
at present has been identified, from specimens 
sent to E. Hill of the British Museum (Natural 
History), as Rattus argentiventer. Until 1954 
no studies of this animal had been made in Min- 
danao. Between then and 1956 a number of 
laboratory examinations made by P. Soriano, 
Bureau of Plant Industry, Manila, showed 
that R. argentiventer could be killed by the roden- 
ticides: sodium fluoracetate, arsenious oxide, 
thallium sulphate, warfarin, tomorin and pival. 
At the same time, field and laboratory studies 
by N.C. Rosell and J.P. Sumaftgil, also of the 
Bureau of Plant Industry, disclosed that these 
rats had a breeding season from July to Decem- 
ber, delivered an average of 4 litters per breeding 
season with about 6 young per litter. 

The main problem was to increase the efficiency 
of control methods. To do this it was necessary 
to study the response of the rats to various 



techniques in the field and for this purpose a 
number of experiments were conducted in the 
wet season during the latter half of 1956 and in 
the dry season during the early part of 1957. 

Although the field experiments were chosen 
primarily to provide a basis on which to adapt 
and recommend methods of control suited to 
local conditions, they also indicate in some 
respects how the behaviour of field rats in Cota- 
bato compares with that of similar rodents else- 
where. 

EXPERIMENTAL METHODS AND DATA 

Spacing of baits The laying of baits in an 
economic manner precludes spending much time 
examining the ground for all signs of the presence 
of rats. This is because the environment includes 
thick undergrowth of grasses, often in marshy 
ground where progress is hampered and the rat 
traces hidden from casual observation. Thus, 
although as much time as possible should be 
given to siting baits in relation to the rat traces 
present, it is necessary to know what minimum 
density of baiting sites will supply a rat popula- 
tion irrespective of the position of rat traces. 

The amount of bait taken by rats from 
containers spaced at various intervals was used 
to compare the effectiveness of different densities 
of baiting sites. At first, baits were placed 20 
metres apart. Twenty-five containers were laid: 
five in each of five rows. Containers were tubes, 
open at each end with a minimum internal 
diameter of 75 mm., made by cutting nodes of 
bamboo. Vegetation covering the baited area 
was mixed. Some of the containers were in 
patches of growing rice and maize or near a 
banana clump, and a few were on ground which 
had been cleared prior to planting but most were 
in uncultivated patches. The uncultivated sec- 
tions included forest trees with undergrowth as 
well as areas of grasses, mainly Saccharum 
spontaneum (2 m. high) and Imperata cylindrica 
(up to 1 m. high) but also some short grass. 
Surplus quantities of bait were used at each of the 
25 sites, uneaten bait was weighed each day and 



t U.K. Ministry of Agriculture, Fisheries, and Food, Infestation Division, acting as Food and Agricultural Organization 
technical adviser in the Philippines. 

34 



VOLUME 19 



ZOOLOGY 



fresh weighed baits replaced. The total nightly 
consumption of the maize meal increased from 
1.5 g. on the first night to 1,120 g. on the twelfth 
night. On the two following nights 932 g. 
and 1,190 g. were eaten. The mean peak con- 
sumption was therefore recorded as 1,090 g. 
For three days following this, baiting sites were 
added so that baits were only 10 m. apart. From 
the nine rows with nine containers each, bait 
consumption was 1,570 g. on the fifteenth night 
and l,760g. on each of the two following nights. 
The mean consumption of 1,700 g. suggested that 
spacing of baits 20 m. apart did not sample the 
population nearly as well as baits at 10 m. dis- 
tances. 

In another experiment a similar procedure was 
adopted but in reverse. That is, baits were laid 
at 10 m. intervals and, after measuring the mean 
peak consumption, a 20m. interval was used and 
consumption compared. With a 10 m. spacing 
in varied vegetation as before, the mean peak 
consumption was 740 g. from the 81 baiting sites. 
This figure was obtained from the results of the 
10th, 12th and 13th nights after baiting com- 
menced, those of llth night were discarded as 
many of the baiting sites were flooded after unusu- 
ally heavy rain. Immediately the number of bait- 
ing sites was reduced, consumption fell to 412 g. 
and in five consecutive nights, varied between 
this and 370 g. the mean consumption being 
400 g. The 25 baits were not sampling the area 
effectively. They were then increased to 36 sites 
spaced 15 m. apart. These were at different 
positions from any of the previous bait sites, and 
the area covered was necessarily slightly smaller. 
Consumption slowly and erratically rose from a 
low level to overtake that achieved from the 
25 baits. Possibly the long conditioning to feed 
at the previous bait sites prevented the usual 
steady rise to a maximum amount of bait eaten 
each night. The mean peak consumption, from 
days 13, 14 and 15 after baiting commenced at 
the new sites was 470 g. These results supported 
the belief that baiting sites as far apart as 15 or 
20 m. would not feed all the rats. Attempts to 
control rats by poison baiting with a density of 
less than 100 bait sites per hectare could therefore 
be expected to be unreliable. 

In these tests it was assumed that the disappear- 
ance of bait from the containers was entirely 
due to rats feeding. There was evidence, such as 
the presence of rat faeces on the surplus food, 
the gnawing of containers, the sight and sound 
of rats visiting baits at night, the clearer demarca- 
tion of runs leading to the baits; that rats were 



responsible for much of the bait consumption 
but it was also evident that ants and perhaps 
many insects could attack the baits. However, 
later use of rodenticides at these plots, followed 
by daily measurement of weighed baits showed 
that consumption could be reduced to between 
zero and 50 g. per day, with consequent disap- 
pearance of rat traces and without evidence of 
change in insect activity. Other investigations 
also indicated that insects did not remove suffi- 
cient bait to affect seriously results obtained. 
In some later experiments there were times when 
monkeys and wild pigs interfered with baiting 
operations but their activities were obvious when 
they occurred and repetition could usually be 
prevented, so that few experiments were vitiated 
by their interference. 

The initial tests did not indicate whether all 
rats within the areas fed from baits even at 10 
m. intervals, nor what proportion of their diet 
the baits provided. Simple, open-plot experi- 
ments could not answer these questions; but 
enclosed areas provided indication later, that it 
was not necessary to site baits as close as 5 m. 
apart. 

Consumption of baits Feeding from containers 
did not commence freely as soon as baits were 
inserted. In areas where no previous baiting 
had occurred, or where containers were moved 
from established positions, the amount of bait 
taken each night was small at first but increased 
each night to a maximum. In twenty different 
baiting trials over a period of ten months it always 
took time to reach maximum consumption, 
sometimes a few days, sometimes several weeks. 
The delay in reaching a maximum could be due 
to one or more of several factors: time taken for 
rats living near the baits to locate them, initial 
avoidance by rats which do find the baits, or 
increasing numbers of rats from a distance finding 
their way to the area. Whatever its cause, it 
was clear that immediate application of poison 
baits in containers could not kill more than a 
small proportion of the rats living in or near the 
area. 

In an attempt to obtain information about 
the relative densities of infestation in various 
habitats, using the amounts of baits taken as an 
index; it was necessary, not only to continue the 
baiting long enough to record a maximum figure, 
but also to standardise the baiting technique. 
After a little experience a standard experimental 
procedure was adopted of providing weighed 
baits in bamboo containers at 100 baiting sites 
set out in ten lines spaced approximately 10 m. 

35 



PROCEEDINGS OF THE NINTH PACIFIC SCIENCE CONGRESS 



apart, so covering a plot of one hectare. Records 
were made of bait taken at individual sites as 
well as total consumption on the plots in order to 
examine the relationship between environment 
and feeding. The mean peak consumption using 
rice binlid (rice shorts) as bait provided a measure 
of the feeding capacity of rats by which the level 
of infestation on different patches of ground 
might be compared. The mean peak consump- 
tion varied from 1.5 kg. to more than 17 kg. in 
various, previously untreated, areas. There was 
no close relation between the presence of crops, 
water courses, or number of observable rat traces 
such as feces, footprints, runways, holes, collec- 
tions of cut stems, or damaged plants; and the 
level of infestation. A fairly high level of infesta- 
tion was present throughout the area with patches 
very heavily infested. In these patches there was 
usually good ground cover, either of crops or 
wild grasses, where rats could run without being 
seen. 

The attachment of rats to covering vegetation 
was noticeable where a baited plot included 
various types of cover: for example, forest, short 
grass, taller grasses and sedges such as Echinchloa, 
Imperata, Polygonum, Scirpus and Sacchamm. 
Much more was eaten from sites among the 
latter plants than the former. Those sites in a 
plot favored by the rats were consistently used. 

When, in the course of providing surplus 
quantities of fresh bait at each site, the capacity 
of a bait container was liable to be exceeded, an 
extra one or more containers, was placed along- 
side the original at the same baiting site. Each 
bamboo tube could hold up to 100 grams of rice 
binlid without suffering too much loss from 
spillage, while the rats fed; but above this figure, 
and at lower figures for bulkier baits such as 
rice bran, extra containers were necessary. 
Sometimes the addition of a container was 
followed by a temporary drop in consumption 
of that baiting site, or a failure to increase the 
nightly consumption as rapidly as expected, but 
this effect disappeared within a day or two. 

Field preference tests The successful applica- 
tion of poison baiting techniques depends as 
much on the choice of baits as on the effectiveness 
of the poisons mixed with them. While such 
factors as availability, cost and ease of prepara- 
tion influence the choice of baiting material, 
the most important factor is the acceptability 
to the species of rat causing the infestation. 
A number of preliminary cage tests were per- 
formed to compare some of the baits, but with 
rats under laboratory conditions preferences were 

36 



affected by previous diet to a much greater extent 
that was the case under field conditions. In the 
field the following materials were tested for 
acceptability: rice bran, cornmeal, rice binlid, 
fresh and dried grated coconut, maize grains 
(dry and boiled) cassava flour, grated cassava 
root, fresh and dried shrimps. 

For each preference test one pair of materials 
was chosen and an infested plot of ground 
selected. Usually twenty baiting sites were 
employed in two lines of ten. The lines were 
ten metres apart, and at ten metre intervals in 
each line, bait containers were positioned close to 
any rat traces which might be found within a 
few metres of the marker. Sketch maps of the 
bait layouts showing type of vegetation and com- 
pass directions were prepared to facilitate loca- 
tion of baits in the undergrowth and to record 
consumption in relation to environment. At 
each numbered baiting site two containers marked 
A and B, were placed side by side to hold the 
two baits. Beginning with 10 gram quantities 
of each, renewed supplies of bait were given 
each day, the quantities being trebled each 
time more than half the previous day's supply 
was eaten. Uneaten residues were weighed to 
enable the amounts taken to be calculated. To 
overcome possible effects due to one container 
being in a more advantageous position than the 
other, they were interchanged each day. Thus, 
if a rat approaching a site from one side, met 
bait A one night: it would meet bait B first on the 
following night. 

Comparisons of the various baits are illustrated 
in the accompanying graphs. 

Bait containers To prevent bait being washed 
away by rain, and to reduce the possibility of 
poison being eaten by domestic animals when 
these are present, containers are used at baiting 
sites. In one test, three types of containers were 
compared. Type A was a bamboo tube about 
8 cm. internal diameter and one internode in 
length, open at each end which was cut slantwise 
to provide an overhang. Type B was of similar 
bamboo but one node was left intact so that one 
end was blocked. Type C was tent-shaped made 
of a wooden frame thatched with leaves and 
provided with a shelf just above ground level. 
Nine rows of nine containers approximately ten 
metres apart were set up. The site was chosen 
for its homogeneity of vegetation. Three of each 
type of container were used in each row and 
their positions in the row were randomly selected. 
The ground was uncultivated, covered with grassy 



VOLUME 19 



ZOOLOGY 



vegetation and, at the time of the test, water- 
logged. Cornmeal was used as a bait and its 
consumption at each baiting site measured. 
After a two week period, during which the total 
amount eaten increased from 50 grams per day 
to 400 grams, the results for the following six 
days from each type of container are summarised 
in the table. 

August. September. 

Date 28 29 30 31 1 2 
Grams taken from 

Type A 332 268 250 179 278 254 

Type B 16 36 21 10 14 35 

Type C 102 274 201 111 123 171 

The superiority of types A and C over the 
containers with one end blocked is obvious. 
There may be an advantage in type A compared 
with the tent-shaped container, type C, but 
there is no statistical significance in the difference 
between results from A and C in this experiment. 
Type A is certainly easier to prepare and trans- 
port when suitable bamboo is obtainable. When 
it is not, a simple inverted v-shaped or u-shaped 
metal cover made from a rectangle 30 cm. x 20cm. 
is satisfactory. 

Comparison between metal covers and bamboo 
tubes was made by a test analogous to a bait 
preference test. At each of twenty baiting sites, 
a pair of containers : one metal, one bamboo, was 
used: equal quantities of rice bran were placed 
in each and renewed daily. Almost equal 
amounts were eaten daily from these two type of 
containers. 

Efficacy of Poisons Preliminary cage tests 
had shown that various rodenticides when 
administered with food were capable of killing 
R. robiginosus. Field trials were chiefly con- 
cerned with measuring the effectiveness of 
methods of poison baiting. The LD 50 for none 
of the rodenticides for this species is known, and 
even if they were there would still remain the 
task of relating lethal dose to palatability in order 
to determine the optimum concentration for 
field work. It would have taken considerable 
time to collect the information necessary for this 
to be done. A quicker initial approach was 
to use various concentrations of the different 
poisons in a series of standard field trials and to 
estimate the proportion of survivors from each 
trial. 

Assessment of the effectiveness of any type of 
treatment in the field resolves itself into obtaining 
a measure of the population before and after 



treatment. This need not be an absolute 
measure but it must be done in such a way that 
comparison of the two results reflects fairly 
accurately the effect of the treatment. Marking, 
and recapture methods can be used to estimate 
rat populations but the process is slow and prob- 
lems due to avoidance of capture can occur. 
Estimates can be based on killing and counting 
the rats in specified areas, carrying out control 
measures in other similar areas, and then killing 
any survivors in the same way as for the initial 
count. A very large number of areas are required 
if a reasonably accurate assessment is wanted. 
The types of environment usually encountered 
provided much too dense a cover for counts of 
live rats seen to be of any value as an index of the 
population, nor were any of the rat traces very 
useful for this purpose: some were difficult to 
find, some e.g. footprints were much affected by 
the amount and time of incidence of rain, this 
species makes relatively few holes especially in 
waterlogged ground where its nests are often 
above ground, hidden among grasses, faeces 
disintegrated rapidly and the use of standard 
dropping boards for counting these did not seem 
satisfactory. 

The method of estimating relative populations 
before and after treatments which was used, 
was based on the census baiting method of 
Chitty and Southern and Doty. At first, these 
estimates of feeding capacity and the treatments 
to be tested were carried out on open experimental 
plots but eventually it was found necessary to use 
enclosed plots. 

Open plot technique A standard sized plot, 
100 metres square, was used and within this one 
hectare, 100 baiting sites were distributed. At 
these sites a bait, different from the one to be 
employed in the treatment, was used to measure 
the daily consumption by rats visiting the baiting 
sites. The amount of bait consumed when the 
maximum was reached and on two succeeding 
nights was averaged to give a pre-treatment 
census figure. The treatment was then com- 
menced using different baiting sites. After the 
treatment, census baiting was again performed 
using the same sites and bait as before the treat- 
ment. Thus a post-treatment census figure was 
obtained and the possibility of bait shyness or 
place shyness affecting the results was avoided. 

This method can give a satisfactory estimate 
of the effectiveness of a treatment only when 
certain conditions are fulfilled: 
1. A large proportion of the rat population 
must take all or most of its food from the baits. 

37 



PROCEEDINGS OF THE NINTH PACIFIC SCIENCE CONGRESS 



2. There must be the same relation before and 
after the treatment between feeding and the 
numbers of animals present. 

3. Movement of rats to and from the area 
involved must not be on such a scale and so un- 
directional as to affect the estimate. 

4. The baits must be free from substantial 
attack by other animals. 

The first and last of these conditions were 
fulfilled. For the second condition there was no 
indication of any marked change of behaviour 
on the part of survivors that would affect the 
results; it was probably fulfilled but there can 
be no certainty of this. Regarding the third 
condition: movement of rats into the baited 
areas frequently occurred with the open type of 
experimental plot first used. It was impossible 
to overcome this difficulty by treating simultane- 



ously the whole of an infestation as this involved 
at least several thousand hectares. Bait barriers, 
sometimes with rows of baits only two metres 
apart, around the periphery of experimental 
plots; could not be relied upon to prevent the 
influx of rats during a baiting period. Thus, 
using the open plot technique, the estimated 
success of various poison treatments was often 
low; the measurement representing a combina- 
tion of survival and inflow of rats after the treat- 
ment. In a few cases the post census figure was 
nil or almost so; that is, invasion of the plot after 
treatment obviously did not occur and the 
prebaiting and poisoning was extremely effective, 
but usually, varied results were obtained. 

So far as these are measures of the effect of 
applying treatments to small patches of a large 
infested area they are worth recording, but they 
do not represent the effectiveness of the poisons :- 



Method of Treatment Pre-census Post census Estimated 

figure figure Success 

Prebait used. Poison used. grams grams 

1. Maize meal. 4% Zinc phosphide. (Initial treatment of plot) 1,700 740 56% 

2. Rice bran. 5 % arsenious oxide (Second treatment of previous plot) 740 40 93 % 

3. Rice bran. 15% arsenious oxide (Initial treatment) 1,000 410 59% 

4. Maize meal. 10% arsenious oxide (Initial treatment 7 days 

pre-baiting) 2,300 32 99% 

5. Maize meal. 15% arsenious oxide (Initial treatment 7 days 

pre-baiting adjacent to previous plot) 2,200 38 98% 

6. Rice binlid. 1.2% thallium sulphate (Initial treatment) 390 240 38% 

7. Rice binlid. 0.4% thallium sulphate (Initial treatment) 430 180 58% 

8. Rice bran. 10% arsenious oxide (Initial treatment) 6,400 1,900 70% 

9. Sodium fluoracetate (Air dispersal of grain soaked in solution of 

rodenticide-direct poison) 7,930 1,640 79% 



Enclosed Plots To determine to what extent 
the increase in consumption of baits each night 
was due to inflow of rats to a baited area, an 
experimental plot was enclosed by a metal 
barrier. The barrier was formed of flat sheets 
of galvanised iron, each 8 feet long and 3 feet 
high. The ends of each sheet were bent at right 
angles to form flanges which were bolted together 
on the inside of the barrier. The sheets were 
embedded 3 inches in dry ground or submerged 
to that extent in water in swampy ground. A 
square area of one hectare was enclosed. Within 
the enclosure bait consumption at 100 sites was 
measured. 

38 



The total amount of bait eaten per night rose 
from 240 grams to 440 grams in the first week 
and on the seventh night nine of the baits 
were completely eaten in spite of putting down 
increasing quantities. Baiting was then discon- 
tinued, from December 21st to January 2nd. 
With the recommencement of baiting 840 grams 
were eaten the first night, 620 grams the second 
night. After that the consumption fluctuated 
between 570 and 890 grams per night during a 
twelve day period, with daily fluctuations between 
30 and 120 grams. Thus there was a process of 
conditioning occurring. Moreover, the practice 
of taking only a little food from containers at 



first and increasing the consumption each night 
was not repeated after the twelve day gap in 
baiting: the rats retained their conditioning. 
After weighing and renewing bait on 14th 
January, one side of the barrier was removed 
and on each of the three following days another 
side was removed. Results were striking. 1,100 
grams of bait were eaten the night after removing 
the first side, and 2,000 grams, 3,100 grams and 
4,500 grams on succeeding nights. It was evident 
that a large number of rats invaded this experi- 
mental plot as soon as the barrier was removed 
and, knowing that this activity could occur, it 
was possible to understand better the results of 
some of the open plot experiments especially 
those where, after a period of two or three 
weeks, consumption had risen to more than 5 kg. 
per night and in one case more than 18 kg. without 
reaching a maximum figure. 

Enclosure of areas permitted a more satisfac- 
tory estimate of the efficacy of poisons. The 
barrier sheets were erected to enclose a square 
with a side of 67 metres and with partitions divid- 
ing the square into four equal compartments. 
The site chosen had a homogeneous cover of 
Imperata. Twenty five baiting sites were usually 
used in each compartment; the sites were approx- 
imately 6 metres apart but positions used for 
treatments differed from those used in testing the 
effect of treatments. Water was placed in small 
troughs at the corners of the compartments in 
dry weather, as the enclosed rats were cut off 
from a ditch, which would normally have been 
accessible. During experimental periods, man- 
agement of the enclosure included inspection of 
the barrier for attempted burrowing and clearing 
of weeds from either side of the metal. Only once 
did burrowing under the enclosure between the 
inside and outside occur. In the compartment 
affected, consumption of bait rose sharply: 
indicating that more animals entered the com- 
partment than left. The rats initially enclosed 
were baited: within a week maximum consump- 
tion was reached in all compartments. Treatment 
with warfarin was completely successful in nine 
days, as shown in table :- 



VOLUME 19 ZOOLOGY 

enclosure free from rats, known numbers could 
be introduced to each compartment. Testing 
of poison baiting could therefore be carried out 
with greater accuracy and without the difficulties 
of interpretation due to influx of rats after the 
treatment. Ten rats were added to each com- 
partment after the warfarin test. Eleven daily 
weighings provided a pre-treatment census figure. 
A prebait and poison treatment using thallium 
sulphate was then carried put followed by 
post-treatment weighings of bait. 



A 
150g. 



B 
HOg. 



C 

85g. 



D 

94g. 



Compartment 
Pre-treatment 

census figure 
Treatment (Bait 

= rice binlid) 

Post-treatment 
census figure 0000 

In open plot tests it was never possible to know 
exactly how many rats were present but with the 



0.025% 0.005% 0.005% 0.025% 
Warfarin Warfarin Warfarin Warfarin 



Compartment 
Pre-treatment 
census figure 
of 10 rats 



Treatment (bait 
= rice binlid) 



Post-treatment 
census figure 



BCD 



I60g. 160g. 170g. results 

discarded 
burrow 
under 
barrier 

0.4% 0.4% 1.2% 1.2% 
thallium thallium thallium thallium 
sulphate sulphate sulphate sulphate 



85g. 



85g. 



47g. 180g. 



Thallium sulphate at these concentrations was 
evidently unsatisfactory. 

Twenty rats were then added to the survivors 
in each compartment, prior to testing zinc phos- 
phide treatments. The results are shown in 
table: 



B 
370g. 



c 



450g. 



D 
510g. 



Compartment A 
Pre-treatment 

census figure 340g. 
Treatment (bait 

= rice binlid) 5% zinc 5% zinc 15%zinc 15% zinc 
phosphide phosphide phosphide phosphide 
Post-treatment 

census figure 9g. 19g. 20g. 

DISCUSSION 

Although the data presented here do not 
permit many unequivocal statements to be made, 
and are quite insufficient to enable a complete 
conception of the general behaviour of the field 
rats in Cotabato to be gained, they do throw 
some light on those aspects of the behaviour 
of rodent pests which are of importance in devis- 
ing control measures in this part of the Philip- 
pines. 

The experimental results show that for poison 
baiting to be consistently successful attention has 
to be paid to the spacing of baiting sites, the type 
and concentration of poison and the type of 
bait. Direct poison baiting with acute poisons 
is less effective than the use of anticoagulants or 

39 



PROCEEDINGS OF THE NINTH PACIFIC SCIENCE CONGRESS 



the placing of acute poisons after prolonged 
prebaiting, partly because the rats in the imme- 
diate neighbourhood of bait containers do not 
eat from them confidently at first and chiefly 
because, after a prolonged period of baiting, 
additional rats from surrounding areas find the 
baits. The foraging range of many of the rats 
probably exceeds 100 metres. At the same time, 
if baits are more than about 10 metres apart a 
proportion of the rats do not feed from them. 
It may be that social facilitation leads to rats 
crowding into a baited area and perhaps individ- 
ual antagonism plays a part in a sparsely baited 
area but this could only be discovered by exten- 
sive behaviour study. 

Of the poisons used, warfarin (0.005%), 
arsenious oxide (10%) and zinc phosphide (5%) 
are effective. Tomorin is similar in acceptability 
to warfarin. Preference tests, similar to those 
used to investigate baiting materials, were carried 
out with several commercial samples of warfarin 
and to compare 0.005% with 0.025% concentra- 
tion. No significant differences in acceptability 
were observed. Thallium sulphate, at the con- 
centrations tested, was less effective than other 
rodenticides. Aerial dispersal of grain soaked 
in sodium fluoracetate has a limited applicability 
in the Philippines. Only one open plot test of this 
method was made and movement of rats into the 
census baited plot after the treatment may have 
accounted for some of the 21% surviving the 
treatment. However, a very large area surround- 
ing the test plot received poison bait at the same 
time: a total of 40 hectares were treated, so any 
rats moving into the test plot came from a 
depleted area. In addition to the main test plot 
two other portions of the 40 hectares were census 
baited, but only after the treatment. This was 
done chiefly to see if any appreciable difference 
occurred between survival in the treated 39 hec- 
tares and survival in the census baited and treated 
one hectare. Rat density was similar in all three 
areas after the air dispersal. 

Among the various possible baiting materials 
some quite strong preferences were shown by the 
rats. Rice and rice binlid were the most accepta- 
ble of the baits tried. Rice bran, boiled maize and 
maize meal were reasonably acceptable. Coconut 
and cassava were of doubtful value. Freshwater 
shrimps were quite unsuitable: addition of these 
to a good bait such as rice binlid reduced the 
palatability. 

Although a field preference test showed that 
rice binlid which had been used in the field and 
then stored again for several weeks was as 

40 



acceptable to rats as unused rice binlid, none of 
the experiments reported here were done with 
re-used baits. For normal control measures of 
course, the use of surplus rice binlid from previous 
treatments is worth practising. 

Despite the high humidity of the environment, 
it was not found necessary to incorporate mould 
inhibitors in baits as a regular procedure, al- 
though some tests with sodium dehydroacetate 
were carried out. There was some evidence that 
feeding habits were affected by rainfall in a man- 
ner similar to that found for Malayan rats by 
J.L. Harrison but this effect was often masked 
by the rising curve of consumption in the baiting 
trials. 

It was not essential to equate bait consumption 
in the field with numbers of rats: experimental 
designs rested on comparisons of quantities, and 
accurate equating would be extremely difficult. 
Figures on consumption of bait by individual 
caged rats were, however, obtained and from two 
series of twenty rats in two laboratories a mean 
consumption of 10 grams (4) per day was 
obtained. It was expected that when known 
numbers of rats were introduced into enclosed 
plots in the field the mean consumption of bait 
would be smaller than this by an amount depend- 
ing on the quantity of naturally occurring food 
which was taken. In fact, the bait taken in the 
enclosures was about 16 grams per rat per day. 
Unless higher figure obtained in the field was 
due to spillage, hoarding, waste or errors of 
measurement, it would seem that the rats were 
not only taking all or most of their nutriment in 
the form of bait but ate more than caged rats. 

SUMMARY 

Poison baiting techniques for the control of the 
local species of field rats are considered with 
special reference to types of bait and poison, and 
method of application. 

REFERENCES 

(1) Chitty, D. and Southern, 1954, "Control of 

Rats and Mice" Vol 1, Clarendon Press, 
Oxford. 

(2) Cole, B.P., 1939, "Quadrat Methods of 

Studying Small Mammal Populations." 
Cleveland Museum of Natural History. 

(3) Doty, 1938, R.E. Hawaii Plant Rec., 42: 

39-76. 



VOLUME 19 ZOOLOGY 



(4) Harrison, J.L., 1949, Effect of rain on the (5) Rosell, N.C. and J.P. Sumangil, 1957, 
feeding of the Malaysian rice field rat. Research Report, Manila B.P.I. 

Nature, 164: 746. 

DISCUSSION 

H.E. MCCLURE: It appears that the best bait is the animals will not eat animal matter, 

one animals were accustomed to eating. R . L STRE CKER: R. rat t us take cacao, but R. exulans 

j. L. HARRISON : In Malaya, R. argentiventer in rice will not. 
fields were best baited by grasshoppers, not rice. But some 



41 



PROCEEDINGS OF THE NINTH PACIFIC SCIENCE CONGRESS 



COMPARISON OF PAIRS OF BAITS 



PREFERENCE TESTS 



B A I T 3 
TAKEN 






RICE BRAN 

/^ 



MAIZE M6AL 



/ 



21 23 25 27 29 1 3 5 
SCp Oct 

100 baiting sites in rice field. 



800 



400 



RICE 



' 



CASSAVA FLOUR 



22 24 26 28 3O I 

Oct Mov 

20 baiting sites, uncultivated ground. 



400 
9 



200 



BINLID 



RICE BRAH 



1234 
NOV 



20 baiting sites near growing rice. 



100 



RICC 
BINLID 



MAIZE GRAINS 



16 17 18 19 20 

Dec 
20 baiting sites in marsh. 



42 



20O 

9- 



COCONUT 



000 
9- 



5OO 



16 >7 Id 19 2O 
Dc 

Coconut fresh at beginning of test. 
No correction for moisture content 
20 baiting sites in marsh. 



Rice 

BINLID 



CASSAVA ROOT 



II 12 
Jon 



2OO 

9- 



2OO 

9- 



13 14 16 16 

20 baiting sites near rice field after harvest. 



RICE BINLID 
DRIED COCONUT 



3 4 

Jan 



56 7 8 9 

20 baiting sites as for fresh coconut. 



CORN 
MEAL 



GRATED CASSAVA 



16 20 22 24 26 28 
Jan 

20 bailing sites among damaged 
growing corn (maize). 



VOLUME 19 



ZOOLOGY 



2 


^ 2 


v 


Kg. 


/ ~ Kg- 


^x/ 


BAIT 
TAKEN 1 


/ RICE 

/ BRAN 

\ '~' 


RICE ^^ 
BRAN X 7 

/ Correct for 




/ 


/BOILED moisture content 




cocowyj 


7 


29 31 2 4 6 29 31 2 4 6 

Jan Feb Jan Feb 
20 baiting sites in grasses. 20 baiting sites in grasses. 


2 

Kg, 


p X 
X 
X 




/BOILED 
^ MAIZE 3OO 




1 


/ (Correct for 9 ' 
. moisture content) 2O 

/ 100 
x COCONUT ^ ^ 


/RICE 

/BINLID 

x^ (partially dries 
N \ s F *?Ri^Jp8 a ^ tcr ^ irst day) 



29 31 2 
Jan Feb 



20 baiting sites in grasses. 



I 2 >3 14 15 
Mar 

20 baiting sites in grasses. 



40O 



200 



Rice 

Binlid , 



RICE BINLID 

RICE BINLID & DRIED SHRIMPS 



2 3 A 5 
APY 

20 baiting sites near maize. 



1400 

9 

12OO 

IOOO 
6OO 
600 
4OO 
200 




Comparison of consumption from 
BAMBOO COVERS & 
METAL COVERS 



18 19 20 21 22 23 24 25 26 27 26 
Jan 



20 baiting sites among maize. 



43 



PROCEEDINGS OF THE NINTH PACIFIC SCIENCE CONGRESS 



RECENT ECOLOGICAL STUDIES ON PLAGUE IN WILD RODENTS IN 
NORTHERN SAN MATEO COUNTY, CALIFORNIA 

S.F. QUAN, L. KARTMAN, and P.M. PRINCE 

U.S. Department of Health, Education, and Welfare, Public Health Service, Bureau of State Services, Communicable Disease 
Center, San Francisco Field Station, San Francisco, California, U.S.A. 



Foci of sylvatic plague, similar to those studied 
in Kenya (Heisch et al., 1953) and in Iran (Balta- 
zard et al., 1952) have been found during the last 
two decades in areas of northern San Mateo 
County, California within a few miles of the 
San Francisco city limits. This particular region 
is a narrow strip of land bounded by San Fran- 
cisco Bay and the Pacific Ocean and characterized 
by low mountains, foothills, valleys, and flatlands. 
Much of the area is residential, either urban, 
or newly suburbanized, and portions contain 
industrial developments. The remainder is 
composed of undeveloped lands scattered in 
valleys, washes, and plateaus, with some farming 
and livestock enterprises. 

According to Meyer (1934) plague was found 
in San Mateo County, California prior to 1934. 
Since that time, investigators from the California 
State Health Department (Unpublished and 
Anon, 1942) and the U.S. Public Health Service 
(Kartman et al., 1958) have isolated Pasteurella 
pestis in northern San Mateo County at various 
times. In recent years the San Francisco Field 
Station, of the U.S. Public Health Service, has 
established several study areas in this region to 
investigate plague ecology. Figure 1 shows 
5 of these study areas; areas A and C are adjacent 
to hog farms, area B is near a dairy, area D is 
close to a meat packing plant and a slaughter 
house, and area E is a wildlife refuge. The first 
4 study areas contain both wild and domestic 
rodents, whereas the last contains only wild 
rodents. P. pestis has been isolated from fleas and 
rodent tissues from areas C and E. 

The principal rodents in these study areas were 
the domestic rat, Rattus norvegicus, the California 
vole, Microtus californicus, the western harvest 
mouse, Reithrodontomys megalotis, the deer 
mouse, Peromyscus maniculatus, and the house 
mouse, Mus musculus. The principal fleas con- 
cerned were Malaraeus telchinum, Catallagia 
wymanni, Hystrichopsylla linsdalei, Atyphloceras 
multidentatus, Opisodasys keeni neshtus, and 
Nosopsyllus fasciatus. 

During 1953-1954 an intensive survey (Miles 
et al, 1957) in the San Francisco region suggested 
that transfer of fleas between various rodent 

44 



species was a significant feature of plague epizoo- 
tiology here. For instance, N. fasciatus was 
found on 18 per cent of M. californicus and on 
12 per cent of P. maniculatus; M. telchinum 
was taken on 5 per cent of Norway rats and these 
two flea species plus C. wymanni occurred on all 
the principal rodents trapped. H. linsdalei and 
A. multidentatus occurred with little discrimina- 
tion on M. californicus and P. maniculatus, but 
were not found on rats. 

Enzootic plague was found in persistent and 
delimited foci which went through periods of 
quiescence, when plague could not be demon- 
strated, to moderate incidence, and occasionally 
to exposive, highly transient epizootic incidents. 
Most of the plague findings were made in areas 
C and E (Fig. 1) where the situation was studied 
most intensively. The presence of P. pestis was 
indicated by animal inoculation of flea pools, 
by culture of individual fleas, and by culture of 
tissues from rodents found dead or moribund. 
The studies suggested that M . californicus was the 
chief plague reservoir since it was parasitized by 
the important vector fleas and by over 90 per cent 
of all species taken. The vectors H. (Hystric- 
hopsylla) linsdalei and M. telchinum were the 
most prevalent species and were found to have 
relatively high natural plague infection rates 
during epizootics (i.e., 2 to 23 per cent, and 4 to 
10 per cent respectively). Experimental studies 
showed that H. linsdalei is an efficient vector by 
individuals with a blocked pro ventriculus, whereas 
M. telchinum transmits primarily by mass mecha- 
nical means. Thus the former may act as the 
primary vector in this region, whereas the latter 
may be a secondary vector especially during 
epizootics. 

Although plague was isolated from tissues of 
M. californicus, there was no evidence of a die- 
off of these rodent populations during an appa- 
rent epizootic period when the percentage of 
infected fleas increased. As a matter of fact, it 
was found that the incidence of plague increased 
during the spring season when the Microtus 
population increased from an average of 6 to 
60 per trap night. These findings contrast with 
the picture of plague in colonial rodents where 



VOLUME 19 



ZOOLOGY 



SAAS 
DALY Or 




Fig. 1. Plague ecology study areas in northern San Mateo Country, California. 



45 



PROCEEDINGS OF THE NINTH PACIFIC SCIENCE CONGRESS 



whole "towns" of prairie dogs or colonies of 
ground squirrels have been decimated (Byington, 
1940). 

In one of the study areas, where wild rodents 
and domestic rats comingled, plague was isolated 
from R. norvegicus during an epizootic in the 
wild rodents (Kartman et al., 1958). One possible 
mechanism of plague transfer from the wild to 
the domestic rodents was indicated by studies with 
radioactively tagged M. telchinum which was 
found to migrate from Microtus to Norway rats 
under experimental conditions (Hartwell et a/., 
1957). The public health significance of these 
ecological findings is seen in areas where subur- 
banization has creasted a period of "joint tenan- 
cy" between wild rodents, domestic rats, and 
humans. Although plague may not be demons- 
trable in some of these areas this does not 
necessarily imply its absence since in one 
study area it was found that plague remained 
quiescent for at least 18 months and then sudden- 
ly became resurgent without prior warning. 

An attempt was made to understand these 
sudden surges in the plague infection rate by 
studying the relative susceptibility of the rodents. 
Small rodents found in the study area were 
trapped alive periodically for laboratory testing. 
Laboratory mice, rats, and guinea pigs were 
used as baseline controls to compare the sus- 
ceptibility of the wild species of rodents. The 
intracutaneous route of inoculation was used in 



these tests because it simulates the flea bite; 
nevertheless, the volume inoculated (0.05 ml) 
was much larger than that injected by a flea. 
The results of these tests revealed a spectrum of 
response varying from very susceptible to highly 
resistant. The results confirmed the data ob- 
tained in a study in Santa Fe, New Mexico 
(Holdenried and Quan, 1956). 

The rodents were classified into four main 
groups according to their relative susceptibility 
(Table 1). It was also found that some rodent 
species may be completely refractory to P. 
pestis inoculations; as the Dipodomys ordii in 
the Santa Fe study. However, no rodent species, 
of which sufficient individuals were tested, was 
found completely refractory in northern San 
Mateo County. 

In all probability, the individuals of the host 
species which are highly susceptible are readily 
infected and die during a plague epizootic. 
Although the terminal sepsis of these dying 
rodents usually will serve to infect more fleas, 
the infected fleas left without hosts have but 
limited opportunities to transmit the infection. 
At the other extreme, individuals of host species 
completely refractory to plague do not develop 
terminal sepsis. However, these refractory animals 
may serve as vehicles in the spread of the 
infected fleas to other species. In species 
belonging to the middle two groups (Table 1) 
some of the infected individuals will die, while 



Table 1. 

Classification of rodent species according to plague susceptibility after intracutaneous 
inoculations of 0.05 ml of a pasteurella Pestis suspension. 



Group 


Succumbed to Approx. Number 


Typical examples 


Virulent 
P. pestis 


Mouse 
LD 50's 


Highly 
susceptible 


1 to 
10 


< 1 
to 1 


Mus musculus, Reithrodontomys megalotis 


Susceptible 
to slightly 
resistant 


10 to 
10,000 


1 to 
1,000 


Microtus californicus* 
Peromyscus maniculatus** 


Moderately 
resistant to 
resistant 


104 to 
107 


103 to 

106 


Rattus norvegicus 


Hightly resistant 
to 
refractory 


> 107 


> 106 


Microtus californicus 
Peromyscus maniculatus 



* From area D only (see Fig. 1). 
Santa Fe, New Mexico. 

46 



VOLUME 19 



ZOOLOGY 



Table 2. 

The seasonal susceptibility to experimental plague of three species of rodents 
from northern San Mateo County, California 



Month, year of test 



Jan. 57 
Feb. 55 
Mar. 57 



Apr. 55 
May 54, 55 

Jun. 55,56 
_______ 

Aug. 55 
Sept. 57 

Oct "54"' 
Nov. 54 
Dec. 56 

Total, average 





Microtus californicus 


Peromyscus 
maniculatus 
(Highly 
Resistant) 

A B 


Rattus norvegicus 
(Resistant) 

A B 


(Highly 
Resistant) 

A B 


(Susceptible) 
A B 




2/31 
8/44 
11/43 


> 106 
> 106 
> 106 


6/7 


< 10-* 


5/25 
2/17 
9/49 


> 106 
> 106 
> 106 


7/16 


105 




5/24 
5/19 
14/42 


> 106 
> 106 
> 106 


17/28 
30/39 


< 104 

< 10 


1/9 

1/34 


> 106 
> 106 


8/12 
8/10 


< 104 
104 




3/19 
2/8 
4/50 


106 

> 106 
> 106 


4/4 
10/21 
0/1 


< 104 
c. 20 


1/10 

7/32 
17/43 


> 106 
> 106 
10 


2/5 
2/4 


< 105 

104 




5/42 
2/17 
23/68 


> 106 
> 106 
> 106 


4/5 


< 104 


4/46 
2/9 

2/42 


> 106 
> 106 
> 106 


12/24 


HH 




84/407 


> 106 


71/105 


< 104 


51/316 


> 106 


39~/71 | 104 



A - Number died/number used. 

B Approx. number P. pestis in LD50. 

others will survive because the number of P. 
pestis transmitted by fleas may be less than the 
lethal dose. In such a pattern fleas would 
have opportunities to become infected on the 
dying rodent. The surviving rodents could not 
only carry and spread the infected fleas, but also 
might harbor plague bacilli either as an inappa- 
rent infection or as a prolonged one. It would 
appear that rodent species in the median resis- 
tant classes may have more important ecological 
roles in the maintenance of wild rodent plague 
than the other classes indicated here. Thus the 
extreme variability in the number of plague 
organisms transmitted by fleas is a possible 
mechanism for the perpetuance of rodent plague. 

Another mechanism, which appears to be 
better substantiated, is the presence of hetero- 
geneity in the susceptibility of a host species. 
Susceptible members of such a species would 
become diseased and infect fleas. The infected 
fleas would transmit the plague bacilli to the 
resistant members, which could serve as reser- 
voirs. Although differences may be shown in the 
susceptibility to plague of Microtus californicus 
and Peromyscus maniculatus, both species were 
highly resistant to P. pestis inoculations. These 
species are found in large numbers in the plague 



foci in northern San Mateo County, California, 
and are considered to be reservoirs for syl vatic 
plague. 

In the last four years approximately 1,200 
live-trapped rodents, primarily 3 wild and 
2 feral domestic species, were tested during 
various months of the year. The LD50's in 
terms of numbers of virulent P. pestis were 
evaluated or estimated, whenever possible, and 
are shown in Table 2. It can be seen that there 
were no significant differences in the LDSO's of 
these species of rodents from season to season. 
Also, there were no differences in the LD50's of 
the more susceptible species of rodents or of the 
laboratory controls. 

Preliminary analyses were also made with 
regard to the influence of age and sex of Microtus 
on susceptibility. These factors showed no sig- 
nificant effects. 

An unusual finding was that the Microtus 
from a small peninsular area (Figure 1, area D), 
of approximately' two to three square miles, 
were susceptible rather than resistant to P. 
pestis inoculations (Quan and Kartman, 1956). 
This area was approximately three miles from 
areas C or E, where Microtus were resistant and 
had been found to be naturally infected with 

47 



PROCEEDINGS OF THE NINTH PACIFIC SCIENCE CONGRESS 



plague. Furthermore P. pestis has not yet been 
found in fleas taken from the D area. One plausi- 
ble explanation for these differences may be 
found in the isolation of this small peninsula by a 
wide, heavily used cement concrete highway. 

During six weeks of a recent epizootic in Area 
C, 61 rodent tissues and 2,202 fleas were cultured 
individually and then pooled for animal inocula- 
tion to test for presence of P. pestis. Of the 
rodents trapped, 293 Microtus californicus made 
up over 90 per cent, and 29 Peromyscus manicula- 
tus made up 9 per cent of all hosts taken. Out 
of 61 rodents found in the traps either ill or dead, 
16 were proved to have plague. The other 
rodents were released at their trap sites and 
periodically recaptured during the study. Out 
of the 2,202 fleas, 1,557 were Malaraeus telchi- 
num;247, Hystrichopsylla linsdalei; 198, Catallagia 
wymanni; and 146, Atyphloceras multidentatus. 
M. telchinum made up 70 per cent of the fleas, 
and the four species mentioned made up 98 per 
cent of all fleas collected. 

The method used for the individual culture of 
the fleas to detect P. pestis was by triturating each 
flea with a glass rod in a small test tube contain- 
ing 0.2 ml of broth, and then streaking a section 
of blood agar plate with the triturate which 
adhered to the rod. The agar plates were incu- 
bated at 28C. After one day, triturates showing 
either P. pestis-like growth or gross contamina- 
tion were segregated and inoculated into animals. 
About 15 to 20 per cent of the fleas had a heavy 
rate of contamination, showing 20 to innumerable 
colonies. Over 50 per cent had but a slight rate 
of contamination, yielding 5 or less colonies of 
microorganisms. No special precautions, there- 
fore, were taken to avoid contamination other 
than keeping dirt from flea collections in the 
field. 

The efficiency range of the culturing method 
was 68 to 87 per cent as compared with the usual 
animal inoculation method which gave a range of 
59 to 98 per cent. The culturing method was 
uniformly sensitive at all levels of P. pestis in the 
fleas, while the animal inoculation method was 
less sensitive to fleas with small numbers of 
plague bacilli. Thus the average efficiency for the 
culture method was 76 per cent, while the animal 
inoculation method, skewed to the higher values, 
was 85 per cent. 

When these two methods were used to detect 
P. pestis, the weekly infection rates in total fleas 
examined were 10.8, 5.6, 4.8, 4.3, 1.5, and 



0.5 per cent, respectively, for six weeks. Although 
some individuals of each of the 4 flea species 
already mentioned (and also Opisodasys keeni 
nesiotus) were found naturally infected, the weekly 
rate of infection in Malaraeus was the only one 
which paralleled the rates above. 

REFERENCES 

Anon, 1942, Plague infection in California and 
Oregon. U.S. Public Health Repts. 
57:1145. 

Baltazard, M., M. Bahmanya, C. Mofida, and B. 
Seydian, 1952, Le foyer de peste du 
Kurdistan. Bull. World Health Org. 
5:441-472. 

Byington, L.B., 1940, Two epizootics of plague 
infection in wild rodents in the western 
United States in 1938. U.S. Public 
Health Repts. 55:1496-1501. 

Heisch, R.B., W.E. Grainger and J. St. A.M. 
D'Souza, 1953, Results of a plague in- 
vestigation in Kenya. Trans. Royal 
Soc. Trop. Med. Hyg. 47:503-521. 

Hartwell, W.V., S.F. Quan, K.G. Scott and L. 
Kartman, 1957, Preliminary observa- 
tions on flea transfer between hosts; 
An important mechanism in the spread 
of bubonic plague, (unpublished). 

Holdenried, R. and S.F. Quan, 1956, Suscepti- 
bility of New Mexico rodents to experi- 
mental plague. Public Health Repts. 
(Washington) 71:979-984. 

Kartman, L., V.I. Miles and P.M. Prince, 1958, 
Ecological studies of wild rodent plague 
in the San Francisco Bay area of Cali- 
fornia I. Introduction. Am. J. Trop. 
Med. Hyg. (In press). 

Meyer, K.F., 1934, Selvatic plague Its present 
status in California. California and 
Western Medicine 40:407-410. 

Miles, V.I., A.R. Kinney, and H.E. Stark, 1957, 
Flea-Host Relationships of associated, 
Rattus and native wild rodents in the 
San Francisco Bay area of California, 
with special reference to plague. Am. 
J. Trop. Med. Hyg. 6:752-760. 

Quan, S.F. and L. Kartman, 1956, The resistance 
of Microtus and Peromyscus to infection 
by Pasteuretta pestis. Trans. Royal 
Soc. Trop. Med. Hyg. 50:104-105. 



48 



VOLUME 19 



ZOOLOGY 



AN INSECTICIDE- BAIT BOX METHOD FOR PLAGUE CONTROL IN 
CERTAIN AREAS OF THE PACIFIC REGION 



LEO KARTMAN 

San Francisco Field Station, San Francisco, California, U.S.A.'t 



Cases of human plague with high mortality 
rates have occurred in a number of Pacific areas 
in recent years (Kaul, 1949; Pollitzer, 1954). 
In Java, outbreaks have been traced to the 
Malayan house rat, Rattus ratios diardi and to 
R. concolor; R. norvegicus also was implicated. 
The flea Xenopsylla cheopis was the principal 
vector (Wilcocks, 1944). In Thailand, R. rattus 
alexandrinus was mainly involved, and R. none- 
gicus was a lesser factor. X. cheopis was the main 
vector (Park, 1941). In Viet Nam, Cambodia, 
and Cochin-China, R. rattus rattus and X. cheopis 
were the principal sources of the infection 
(Pollitzer, 1954). However, in 1943 domestic mice 
and X. cheopis were implicated in a limited out- 
break at Saigon (Herivaux and Toumanoff, 1948). 

In combating plague, it is now generally recog- 
nized that flea control should be carried out 
concomitantly with rodent control for the best 
result (Gordon and Knies, 1947; Kartman and 
Lonergan, 1955). In some cases flea control 
alone has been used with marked success (Mac- 
chiavello, 1946; McKenzie Pollock, 1948). Thus 
schemes for the simultaneous control of rodents 
and their fleas should be used as additions to 
a general program of plague control. It is 
fortunate that no significant resistance to DDT. 
or other insecticide has been noted in X. cheopis 
or in any other important flea vector of plague. 
DDT remains the insecticide of choice for plague 
and murine typhus control. Field tests have 
shown that a 5 per cent DDT dust is about 
as effective for the control of X. cheopis as a 
10 per cent dust (Simmons, 1955). 

Experience with an insecticide-bait box has 
shown that both domestic and wild rodents can 
be controlled with warfarin and that their fleas 
can be controlled with DDT powder picked up 
when the rodents visit the bait boxes (Kartman 
and Lonergan, 1955). More recent work with 
simplified bait boxes has shown that the fleas on 
various species of field mice are controlled both 
on the rodents and in their nests (unpublished). 
Direct evidence shows that rodents, which pick 
up DDT powder in the bait box, transport enough 
of it to their nests to kill the fleas there. 



It is the purpose of this communication to 
recommend an insecticide-bait box for use in 
plague control in the Pacific region. Figures 
1 and 2 are illustrations of a bait box which may 
be used in a combined operation of rodent and 
flea control. This is a simplified version of the 
bait box used in Hawaii (Kartman and Lonergan, 
1955) and has been designed for greater ease of 
transport, low cost, and ease of maintenance. 

These bait boxes can be placed at rodent holes 
and along rodent trails near buildings, in build- 
ings, or in the field. In the field, they may be set 
from 35 to 50 feet apart when small rodents are 
involved, and from 50 to 75 foot intervals when 
larger species are the principal targets. Spacing 
of the boxes depends upon knowledge of the home 
range of the rodent. Placement of the boxes 
in and around buildings, on the other hand, 
depends primarily on locations near rat runs and 
holes. The usual method for control of fleas 
in buildings consists of dusting living quarters, 
outbuildings, attics, cellars, etc. with a 5 or 10 per 
cent DDT dust or a 5 per cent DDT spray where 
rats are known to be present. When indicated, 
DDT dusting of individuals, clothing, bedding, 
furniture, and domestic animals may be used. 
The bait box method in buildings can be used as 
a supplementary measure for ease of long term 
operation, and also in situations where the 
wholesale dissemination of DDT dust is contrain- 
dicated because of social or personal objections. 

When used, the bait boxes are first placed in 
the area with unpoisoned food (rolled oats, etc.) 
for a one week pre-baiting period. Then a layer 
of 5 or 10 per cent DDT powder in pyrophyllite 
is spread uniformly on the floor board of each 
bait box (about 80-90 grams per box is sufficient). 
This is allowed to operate for about 4-6 days when 
the bait is changed to warfarin-treated rolled oats. 
The bait boxes are examined periodically to add 
DDT and bait when necessary. The length of the 
operation depends upon information gathered 
from periodic trapping of rodents to determine 
their prevalence and their flea indices. Examples 
of flea control data, obtained in field tests of the 
bait box method, are shown in Tables 1 and 2. 



t From the Communicable Disease Center, Public Health Service, U.S. Department of Health, Education, and Welfare, 
Atlanta, Georgia. 

49 



PROCEEDINGS OF THE NINTH PACIFIC SCIENCE CONGRESS 




Fig. 1. End view of bait box showing bait container and DDT powder on floor; the bait box consists of a floor board 
1/2 inch thick, 12 inches long, and 8 inches wide; it is covered by a U-shaped roof made by cutting a lard tin 
(9 1/2 inches in diameter and 121/2 inches deep) in half lengthwise; the roof may be fastened to the sides of the 
floor board or simply placed over the floor without fastening. 



50 



VOLUME 19 



ZOOLOGY 




Fig. 2. Side view of bait box showing DDT powder trails extending from both ends; note a vole, Microtus californicus, 
which has just left the box. 



Table 1. 

Effect of 5 percent DDT powder in bait boxes on the incidence of fleas 
on Microtus californicus in San Francisco. 



Period. 


Treated Plot 
(DDT-Treated Bait Boxes 
Aug. 27 to Sept. 27) 


Check Plot 
(150 Feet From DDT-Treated Plot) 




No. Percent 
Dates Animals/ Mean Microtus 
('56-'57) No. Fleas Fleas Infested 


No. Percent 
Dates Animals/ Mean Microtus 
('56-'57) No. Fleas Fleas Infested 


Pre-treatment 
Treatment 
Post-treatment 

5? 
) 

> i> 


8/15- 8/23 64/343 5.4 92.2 
9/5 - 9/26 162/2 0.01 1.2 
10/2 -10/17 206/63 0.3 21.4 
10/23-11/27 239/274 1.1 50.6 
1/8 - 2/7 56/59 1.0 41.1 
3/19- 5/2 63/58 0.9 42.8 


8/8 - 8/9 6/49 8.2 54.5 
9/11- 9/13 27/200 7.4 78.3 
10/9 -10/17 32/176 5.5 99.9 
10/23-11/27 109/564 5.2 88.9 
1/8 - 2/7 40/126 3.2 82.5 
3/19- 5/2 34/46 1.3 52.9 



51 



PROCEEDINGS OF THE NINTH PACIFIC SCIENCE CONGRESS 

Table 2. 

Effect of 5 percent DDT powder in bait boxes on flea incidence in nests of Microtus Californicus 

during the post-treatment period. 



Treated Plot 


Check Plot 


DDT-Treated Bait Boxes Aug. 27 to Sept. 27 


(150 Feet From DDT-Treated Plot) 


Date 

C56-'57) 


Days 
After 
Treat. 


No. 
Nests 


Mean Fleas 
per 


Mean 
amt. 
DDT 
(mg.) 


Date 
('56-'57) 


Days 
After 
Treat. 


No. 
Nests 


Mean Fleas 
per 


Mean 
amt. 
DDT 
(mg.) 


Nest 


Infest. 

Nest 


Nest 


Infest. 

Nest 


10-5 


8 


7 


0.1 


1.0 


2.1 


10-17 


20 


7 


9.0 


12.6 





12-19 


83 


4 


0.2 


1.0 


1.1 


12-19 


83 


3 


14.6 


22.0 





2-6 


132 


3 








1.0 


2-6 


132 


4 


11.5 


12.0 





4-10 


195 


4 


33.5 


33.5 





4-10 


195 


4 


38.5 


77.0 






In view of the fact that certain materials may 
not be available in some countries, it should be 
emphasized that modified versions of the bait box 
may be constructed from local materials. Thus 
in some areas large bamboo sections can be used 
for bait boxes. A small hole cut in the center of 
the bamboo (with plug when not in use) can be 
used to pour the bait into a small container 
secured at the center inside the bamboo tube. 
The DDT powder may be spread inside the bam- 
boo section from both ends. Actually, many 
materials can be used to make the bait boxes. 
The principal consideration must be given to 
construction which protects the DDT from rain, 
and to bait box dimensions which accomodate 
both the smallest and largest rodents involved. 
As an adjunct to other operations, the insecti- 
cide-bait box method offers a cheap and efficient 
means of reducing the number of rodents and 
their fleas in rodent-borne disease control. 

REFERENCES 

Gordon, J.E. and Knies, P.T., 1947, Amer. J. 

Med. Sci. 213:362. 
Herivaux, A. and Toumanoff, C., 1948, Bull. Soc. 

Path. Exot. 41:47. 



Kartman, L. and Lonergan, R.P., 1955, Bull. 

Wld. Hlth. Org. 13:49. 
Kaul, P.M., 1949, W.H.O. Epidem. Vital Statist. 

Rep. 2:142. 
Macchiavello, A., 1946, Amer. J. Publ. Hlth. 

36:842. 

McKenzie Pollock, J.S., 1948, Trans. Roy. Soc. 

Trop. Med. Hyg. 41:647. 
Park, C.L., 1941, Bull. Off. Int. Hyg. Publ. 

33:400. 
Pollitzer, R., 1954, Plague. W.H.O. Monograph 

No. 22. 
Simmons, S.W., 1955, Rev. Ingeniera Sanit., 

Ano. 9:60. 
Wilcocks, C., 1944, Trop. Dis. Bull. 41:626, 

795, 890, 986. 

DISCUSSION 

H.J. COOLIDOE: How long does effects of DDT 
dusting last? 

K.F. MEYER : About four weeks. 

H.E. MCCLURE: Any flea resistance to DDT? 

K.F. MEYER : No. Very rare in fleas. 



52 



VOLUME 19 



ZOOLOGY 



OBSERVATIONS ON RODENT PLAGUE IN HAWAII 



BERTRAM GROSS 

Chief, Bureau of Rodent Control, Department of Health, Territory of Hawaii, Honolulu, Hawaii. 

(Abstract) 



1 . The present status of plague infection in the 
known endemic plague region of the Hamakua 
District, Island of Hawaii, T.H., is reviewed. 

2. A twenty-four year rodent retrieval record 
is presented. The data show that although the 
rodent species composition may vary from area to 
area, the native Hawaiian rat, Rattus hawaiiensis 
Stone, constituted 60.1 per cent of all rat retrievals 
and was the predominant rat species found in this 
plague region. 

3. A tabulation of the extent of plague infec- 
tion detected among the rodent species during the 
same period revealed that plague is found in all 
rodent species present and that 69.7 per cent of 
the infections detected were in R. hawaiiensis. 

4. Figures on the seasonal incidence of rodent 
plague covering a forty-six year period showed 
that plague infection has been detected most often 
during the months September through March. 
It is pointed out that plague in rodents or their 
fleas has occurred every month of the year and 
that from a practical standpoint surveillance and 
suppressive measures must be undertaken through 
out the year. 

5. Seven species of fleas are present. The 
three species most frequently found on rodents 
are Xenopsylla cheopis, Xenopsylla vexabilis 



hawaiiensis and Leptopsylla segnis. All five of the 
rodent species present are infested by these three 
species of fleas. 

6. The rodent flea patterns varied greatly 
from area to area. There were certain areas far 
removed from buildings where X. cheopis were 
found and X. vexabilis hawaiiensis were not. The 
reverse was true in other areas. This indicates 
that small geographical differences within this 
plague region may influence the flea patterns. 

7. A study of the distribution of fleas among 
rodents cage trapped in three separate field areas 
showed that R. norvegicus is consistently more 
highly parasitized with X. cheopis and X. vexabilis 
hawaiiensis than are the other rodent species. 

8. Data presented do not support the conten- 
tion of other workers that the outdoor X. cheopis 
index in the Hamakua plague region is low and 
inadequate for the spread of plague and, there- 
fore, the role of X. cheopis in the perpetuation of 
plague in the fields assumes greater importance. 

9. The desirability and possibility of evolving 
a low cost method of applying insecticides to 
rodent burrows and nests in the field is discussed. 

10. Plague suppressive measures are evaluated 
including the application of insecticides and the 
importance of good sanitation and inhousing. 



DISCUSSION 



w.w. CANTELO: Type of baits and bait stations? 

B. GROSS: Trap lines are 50 feet apart with poison 
stations at midpoint. Two types of poison utilized: (a) 
bread and phosphorus, and (b) zinc phosphide with rolled 



oats, wheat, or barley at cone, of -J- Ib. zinc phosphide 
per 100 Ib. grain with addition of lime. Zinc torpedoes are 
broadcast by hand in caves and gulches. 



53 



PROCEEDINGS OF THE NINTH PACIFIC SCIENCE CONGRESS 



PLAGUE IN THAILAND 



MALI THAINEUA 

Provincial Health Officer, Vbon, Thailand. 

(Abstract) 



Plague has been endemic in Thailand for 
many years. The first case was reported in 
Bangkok in 1904. The infection was believed 
to have been imported from India. No definite 
records were available before 1913. There were 
two waves of plague epidemic from 1913 to 
1934 and from 1938 to 1952 respectively. A 
severe epidemic occurred in Korat in 1917 and 
more than 500 deaths were reported. Surprisingly 
there was not even a single case of plague 
reported from the southern part of Thailand. 
This may be due to incorrectness of reporting. 

From 1938 plague cases have been reported 
every year. In 1952 it was decided that 



greater effort should be made to control the 
disease. Therefore with the aid of ICA in 1952 
three permanent laboratories for detection and 
control of rat-born diseases were established in 
three plague endemic areas in Thailand. The 
following methods of control were carried out> 
DDT dusting and spraying for keeping down 
the X. cheopis population, rat poisoning-trapping, 
and improving sanitation by eliminating rat har- 
bourage. These three laboratories with good 
co-operation from the local authorities were very 
successful in this campaign and no single human 
case of plague has been reported since 1953. 



DISCUSSION 



J.L. HARRISON 

most? 

M. THAINEUA I 



Where does Rattus rattus thai occur 



Open rice fields and houses. 
A.O. SEARLE: Does Rattus r. tikos occur here? 
J.L. HARRISON: May be same as R.r. thai. 
Bandicoots enter houses here? 
M. THAINEUA : Very rarely. 



Do 



J.L. HARRISON: Suspects bandicoots involved in 
plague in Rangoon. 

A.O. SEARLE : Is housemouse white bellied or grey or 
brown bellied? 

J.L. HARRISON: Same as Malayan ones, grey. Are we 
equating R. hawaiiensis with R. exulansl 

B. GROSS: Yes. Comments then given on appearance 
and life habits of this rat. 



54 



VOLUME 19 



ZOOLOGY 



Symposium: Contributed Papers in Zoology 



JAPANESE EXPEDITIONARY ACTIVITIES IN BIOLOGICAL SCIENCES 

IN POSTWAR ASIA 

TADAO UMESAO 

Laboratory of Ecology, Institute of Polytechnics, Osaka City University, Osaka, Japan. 



This paper intends to introduce to the atten- 
dants of the present Congress 4 he activities and 
results of the recent Japanese expeditions in 
Asia, which are as yet little known in other coun- 
tries, with special references to biological sciences, 
including botany, zoology, and anthropology. 

Before the War, the Japanese people had their 
main interests in the Continent, the countries of 
the northeastern part of Asia, Korea, Manchuria, 
Mongolia and China. In these areas, Japanese 
scientists had carried out the active works in the 
fields of the basic sciences as well as the applied 
sciences. 

After 1944, however, it has become almost 
impossible for the Japanese scientists to continue 
their works in these areas. They have turned 
their eyes to the southern part of Asia. 

Geographically speaking, the countries of 
South-East Asia are very near from Japan. But, 
after the War, there have been some difficulties 
for Japanese to perform scientific field works in 
these areas. To the regions of South East Asia, 
I will mention later. The earliest post-war 
expeditions from Japan concentrated to the 
mountainous area of northern India. 

In the following review, two regions are 
especially mentioned. The one is Central Nepal 
and the other is the Karakoram-Hindu Kush 
Range extending from West Pakistan to Afgha- 
nistan. 

NEPAL HIMALAYA 

In 1951, some scientists of Kyoto University 
organized the Fauna and Flora Research Society 
(FFRS) to investigate the little known parts of 
Asia and above all the Himalayas in cooperation 
with the Academic Alpine Club of Kyoto 
(AACK). Now, the society includes twenty one 
professors of three universities in Kyoto and 
Osaka. After the establishment, the society 
began at once to organize a scientific expedition 
to Central Nepal Himalaya under the president- 
ship of Dr. Isawo Namikawa, Prof. Emeritus of 



Kyoto University. The plan was later accepted 
by the Japanese Alpine Club (JAC) and in 
1952 a reconaissance party was sent by JAC to 
Nepal in order to find out a possible route to the 
summit of Manaslu (8125 m), one of the least 
known peaks of so-called Himalayan Giants at 
that time. On the trip round Manaslu Massif, 
the reconaissance party successfully found a 
promising climbing route on the eastern slope 
of the peak. From 1953, on the climbing party 
of JAC began the assault on Manaslu, and after 
several frustrated trials, the Japanese party 
finally reached the summit in May 1956. 

The 1952 reconaissance party was headed by 
Dr. Kinji Imanishi, an FFRS member known as 
eminent ecologist and alpinist in Japan. Anothor 
member of the soiety, Prof. S. Nakao joined 
the party as botanist. They brought back a 
considerable amount of biological collections. 
To the first climbing party of 1953, FFRS again 
sent two members, Prof. Nakao and Prof. J. 
Kawakita, a geographer. They skirted around 
the three great massifs of Nepal Himalaya, the 
Annapurana, the Manaslu-Himal Chuli and the 
Ganesh Himal. Botanical collections of the 
preceding year was greatly enriched by Nakao, 
and Kawakita made an extensive observation 
on the anthropology of the region. An anthro- 
pological collection was brought back for the 
Ethnological Museum of Tokyo. 

In the postmonsoon season of the same year, 
a small party of AACK attacked Annapurana 
IV (7525 m), but was driven back by strong wind 
at 7200 m. Two members of the party were the 
students majoring in horticulture. They also 
brought to Kyoto University specimens and seeds 
of wild and cultivated plants as well as some 
insects. 

The materials collected by these expeditions 
were entrusted to FFRS and thoroughly inves- 
tigated by the members of the society and many 
other specialists in Japan. The results have been 
published by the society in three volumes, 
"The Scientific Results of the Japanese Expedi- 

55 



PROCEEDINGS OF THE NINTH PACIFIC SCIENCE CONGRESS 



tion to Nepal Himalaya 1952-53" edited by 
Dr. Hitoshi Kihara, Director of the National 
Institute of Genetics. They are written in Eng- 
lish and include some 1400 pages. 

The first volume is "Fauna and Flora of Nepal 
Himalaya (1955)." Most of the volume is dedi- 
cated to the taxonomy of plants and insects col- 
lected during the expeditions. Collection of 
plants not only phanerogamous but also ferns, 
mosses, fresh water algae and lichens, was 
most complete. For general information, the 
number of collected plant species is enumerated 
in table 1. 

Considering the restricted area and season of 
the collections, this result, especially the high 
percentage of new and newly recorded species, 
should be evaluated. The number of phanero- 
gamous species listed in Landon's Nepal (1928) 
was 1672. 

According to Prof. Kitamura, who compiled 
vascular plants in the volume, the alpine flora 
of Himalaya is closely related to those of Eastern 
Tibet, Western China and partly Formosa. It is 
also very interesting that some plants collected 
by Rev. Ekai Kawaguchi, a Japanese Buddhist 
who visited Tibet through Central Nepal in 1899- 
1900, were rediscovered by the present expedi- 
tions and one of them was new to science. 

The zoological collections from Nepal are not 
numerous and restricted to insects owing to 
various difficulties in collecting. Butterflies, 
dragonflies, fruitflies, mayfly nymphs and rice 
weevils were described by 5 experts. The 
number of butterfly species collected amounted 
to 100 and many of them were new to Nepal. 

Prof. Nakao presented a brief note on the 
natural vegetation of central Nepal Himalaya. 



And, at the top of the second volume "Land and 
crops of Nepal Himalaya (1956)", Prof. Kawakita 
described the major types of vegetation in detail 
as related to climatic and edaphic conditions. 
He recognized 6 altitudinal zones of vegetation 
from the subtropical forest (evergreen seasonal 
forest) of sal tree to the alpine zone. To the west 
of the Manaslu Massif, the climate tends to be 
arid and dense forests of subalpine and temperate 
conifers gradually give way to open woodland 
of pine and juniper, and finally to the desert-like 
vegetation composed of dwarf brushes armed 
with thorn or spikelets. 

Native agriculture of Nepal was studied by 
Kawakita and Nakao. The former thoroughly 
analysed the crops zones along altitudinal gra- 
dient and discussed the influence of climatic and 
cultural factors upon the cropping system. He 
also made some suggestions on the agricultural 
improvement. 

Cultivated plants in Nepal were studied. They 
are mostly collected as seeds and grown for 
observation in Japan. Some 30 specialists, 
including one from U.S.A., present the result 
of morphological, taxonomical, cytological and 
agroecological studies on rice, maize, wheat, 
barley, oat, African millet, and some other 
cereal crops, grain Amaranthus, buckwheat, 
hemp, morning-glory, legumes, several kinds of 
vegetables, etc. Several materials of native 
plant drugs were also studied. 

According to Dr. Namikawa's generalized 
statement, not any characteristics of the Nepalese 
crop varieties seem useful for the improvement of 
Japanese varieties. Nepalese varieties of legumes, 
cucumbers and other crops are either very late 
to flower or easily susceptible to pests under 



Table 1. 
Plants collected by the Japanese Himalayan Expeditions 1952-53. 



Investigator 
S. Kitamura 



Y. Horikawa 
M. Hirano 
Y. Asahina 



Materials 


Species 


New species 


New variety 
and form 


Remark 


Ferns 


^4 

J*T 










Gymnospermae 


14 










Angiospermae 








Ca. 300 


Monocotyledoneae 


110 


3 





species 


Dicotyledoneae 


812 


34 


15 


are new 


Characeae 


2 








to Nepal 


Mosses 


62 










Freshwater algae 


184 


i 


4 




Lichens 


62 


2 


1 




Total 


1,280 


40 


20 





56 



Japanese climate. They are more or less primi- 
tive in their characters as compared with Japanese 
crops. 

The third volume of the Scientific Results of 
the Expeditions includes above all the comprehen- 
sive account of Prof. Kawakita's ethnogeograph- 
ical study on the natives. He describes the dis- 
tribution of ethnic and cultural elements along 
his route, agriculture, animal husbandry, trans- 
portation and commerce, settlement, territorial 
organization, tribes and castes and so forth. 
Special attention is paid to the religions of both 
Hinduistic lowland and Lamaistic highland and 
he points out the possible existence of a primitive 
shamanistic religion among mountain inhabitants 
which still survives as relict under the recent 
predominance of the two powerful religions. 
He made the intensive survey of a Tibetan village, 
Tsumje, situated at the altitude of ca. 3500 m on 
the uppermost reaches of Buri Gandaki (River). 
He stayed there for 40 days studying all phases of 
its life. A tentative conclusion on the structure 
of Tibetan life contains many interesting and 
original points of view, but it may take too much 
space and time to introduce only the outlines. 

Mr. Y. Huzioka also contributes to the volume 
on the results of Rohrschach test obtained from 
the inhabitants of Tsumje, a Tibetan village. The 
personality make-up of the village, he concludes, 
is isolative, more self-gratifying than social. 
Other aspects of the study will be presented by 
the author himself at the present Congress. 

KARAKORAM-HINDU KUSH RANGE 

Let us now turn to the second area, Karako- 
ram-Hindu Kush. In 1955, Kyoto University 
sent the Kyoto University Scientific Expeditions 
to Karakoram and Hindu Kush (KUSE 1955) 
under the general leadership of Prof. Kihara. 
12 sceintists including a surgeon, most of which 
were the members of FFRS, 2 cameramen, a 
reporter, a liaison officer from Pakistan and two 
interpreters from Pakistan and Afghanistan 
constituted the expedition. During the period 
from April to October, the expedition covered 
in several parties the extensive area through 
India, Pakistan, Afghanistan, Iran and finally to 
the southern coast of the Caspian Sea. 

The Karakoram party headed by Dr. K. 
Imanishi travelled through high peaks of central 
Karakoram along the three magnificent glaciers, 
Hispar, Biafo and Baltoro, and carried out geo- 
logical, botanical and anthropological investiga- 
tions. Two geologists also traversed the upper 



VOLUME 19 ZOOLOGY 

reaches of the Indus River from Gilgit to Askole. 
Geological studies are now continued in adjacent 
area as stated later. 

Other members of the expedition entered 
Afghanistan from the Baluchistan border in 
early June. One of the main object of the 
botanical party was to collect materials in order 
to verify the hypothesis of Dr. Kihara on the 
origin of cultivated wheat. From his long years' 
genetical and cytological study, he reached the 
conclusion that the cultivated wheat (Triticum 
vulgare) must have originated from the hybridiza- 
tion between Emmer wheat and Aegilops squar- 
rosa, a close relative of the genus Triticum. 
Actually he succeeded by crossing these 
two species in the artificial synthesis of 
new hexaploid wheat, which closely resembled 
Triticum vulgare in their morphology. He 
considers that the cultivated wheat had most 
probably appeared at least 4000 years ago in 
Transcaucasus, where the ranges of distribution 
of wild Emmer and Aegilops squarrosa overlap 
each other. Throughout their long travel from 
Quetta of Pakistan along ancient Silk Road to 
the Caspian Sea, Dr. Kihara and Prof. K. Yama- 
shita found Aegilops squarrosa growing every- 
where as weed in wheat fields, and in some 
restricted localities growing together with cul- 
tivated Emmer wheat. Many specimens of squar- 
rosa and other species of Aegilops were brought 
to Japan and are now under investigation. But 
their experiences seem to support Kihara's 
hypothesis that Transcaucasus must have been 
the native place of cultivated wheat. 

Another member of the botanical party was 
Prof. Kitamura of Kyoto University. He made 
several collecting trips from Kabul in the eastern 
half of Afghanistan. Experiences in Nuristan or 
the southern slope of central Hindu Kush were 
especially fruitful, where he found the western- 
most extention of the Sino-Japanese Flora. 
Abundant collections of wild and cultivated 
plants from Karakoram-Hindu Kush Range are 
now being studied by several Japanese experts. 

The anthropological party of the expedition 
was composed of four Japanese members. As a 
human ecologist I joined the party. The main 
aim of the party was the discovery and research 
of Mongolian tribe in Afghanistan. It has long 
been known since 1906 that there lives some- 
where in Afghanistan a Mongolian tribe, Moghol 
as the tribe is called in Afghanistan, speaking 
apparently Mongolian language, but no one has 
yet succeeded in visiting its native land. 

57 



PROCEEDINGS OF THE NINTH PACIFIC SCIENCE CONGRESS 



The expedition succeeded in discovering the 
village of Moghols in the midst of Ghorat District, 
a mountainous region of West Afghanistan. Lin- 
guistic and ethnographical research was carried 
out. Plant and insect specimens brought back 
to Japan may be the first collection from the dis- 
trict. 

The collections and materials brought by 
KUSE are now studied in Japan supported by 
financial aids from the Ministry of Education. 
The scientific results will be published from 
next year onwards by FFRS. 

In 1956 and 1957, the Exploration Club of 
Kyoto University sent two small expeditions to 
Eastern Hindu Kush in cooperation with Punjab 
University, Lahore, Pakistan. Japanese members 
of the 1956 party consisted of two students in 
biology and Assist. Prof. K. Huzita of Osaka 
City University who was a geological member of 
the Karakoram Party of 1955. They covered the 
area west of the Hunza River. In this year, 
Prof. S. Matushita, who collaborated with four 
Japanese students in geology and forestry, visited 
Swat Province, a little known tribal territory on 
the northwest border of Pakistan. Several 
geologists and botanists of Punjab University 
also joined the party. 

In ending this brief review, I wish to tell you 
that our interest is now turning to S.E.-Asia 
especially to the regions covered by primaeval 
forests. Post-war activities of Japanese scien- 
tists in these areas are almost nil. 

In the early months of this year, two agro- 
nomists from Hyogo Agricultural College visited 
Laos, Cambodia and Viet-nam, with special 
interest in rice cultivation in these areas. 

On the problem of rice cultivation, a new 
attempt is being made. The Ethnological Society 
of Japan organized an expedition which intends 
to collect ethnographical data of rice cultivating 
peoples of these areas. They are now working 
in Laos and Cambodia. Although most 
members of the expedition are of the cultural 
sciences, such as linguists, ethnographers, and 
historians, two of them are specialists of morpho- 
logy and genetics of rice. The Society will con- 
tinue the work in the following years. 

The latest one is the Osaka City University 
Biological Expedition to South East Asia. I 
and my five colleagues are staying in Bangkok. 
All members are ecologists. Two of them are 
plant, two are animal and the other two are 

58 



human ecologists. At least three members of 
Chulalongkorn University will join us. After 
the Congress is over, we are going to start 
towards northern part of Thailand, and later, 
visit Laos, Cambodia and Viet-Nam. 

REFERENCES 

Huzita, K. and Hayasida, S., 1956, Karakoram. 
Asahi Photographic Books 30. The 
Asahi Press, Tokyo and Osaka. 

Imanishi, K., 1953, Nature in Nepal Himalaya. 
Kagaku 23: 405-516, 464-468. 

Imanishi, K., 1954, On the Himalayas. Haku- 
suisha Pub. Co., Tokyo. 

Imanishi, K., 1956, Karakoram. Bungeishunju- 
shinsha Pub. Co., Tokyo. 

Iwamura, S., 1955, Afghanistan Journeys. The 
Asahi Press, Tokyo and Osaka. 

Iwamura, S., 1955, Afghanistan. Asahi Photo- 
graphic Books 12. The Asahi Press, 
Tokyo and Osaka. 

Iwamura, S. and Schurmann H., 1955, Notes on 
Mongolian Groups in Afghanistan. Zin- 
bun. The Research Institute for Huma- 
nistic Studies, Kyoto University. Kyoto. 

Iwamura, S. and Okazaki T., 1957, Iran. Asahi 
Photographic Books 40. The Asahi 
Press, Tokyo and Osaka. 

Japanese Alpine Club, 1953, Nepal Himalaya. 
Iwanami Photographic Books 88. Iwa- 
nami Pub. Co., Tokyo. 

Kihara, H. ed., 1955-57, Scientific Results of the 
Japanese Expeditions to Nepal Hima- 
laya 1952-53. Fauna and Flora Re- 
search Society, Kyoto University, Kyoto. 

Vol. I. Fauna and Flora of Nepal 
Himalaya. 1955. 

Vol. II. Land and crops of Nepal 
Himalaya. 1956. 

Vol. III. People of Nepal Himalaya. 

1957. 

Kihara, H. ed., 1956, Exploration through 
Deserts and Glaciers. The Asahi Press, 
Tokyo and Osaka. 

Umesao, T., 1956, In Search of the Moghols. 
Iwanami Pub. Co., Tokyo. 

Umesao, T,, 1956, Travels in Afghanistan. 
Iwanami Photographic Books 202. 
Iwanami Pub. Co., Tokyo. 



VOLUME 19 



Year 

1952 
1953 
1953 
1954 
1955 
1956 
1956 

1957 
1957 
1957 
1957 



Japanese expeditions covering biological fields in post-war Asia. 



ZOOLOGY 



Region 

Central Nepal 

Central Nepal & Manaslu 

Annapurna IV 

Manaslu & Ganesh Himal 

Karakoram & Hindu Kush 

Manaslu (ascent) 

Eastern Hindu Kush 

Swat Himalaya 
Cambodia & Laos 
South East Asia 
South East Asia 



Leader 

K. Imanishi 
Y. Mita 
T. Imanishi 
Y. Hotta 
H. Kihara 
Y. Maki 
K. Huzita 
H. Begg 
S. Matsushita 
S. Sato 

N. Matsumoto 
T. Umesao 



Organization 

JAC 
JAC 
AACK 
JAC 

Kyoto Univ. 

JAC 

Kyoto Univ. 

& Panjab Univ. 

Kyoto Univ. 

Hyogo Agricultural College 

Ethnological Society of Japan. 

Osaka City Univ. & Chula- 

longkorn Univ. 



DISCUSS/ON 



N.A MEINKOTH: Any zoological work done on the 
expeditions to Nepal and Afghanistan? 

T. UMESAO: Yes, results will be published later. 

E.H. TAYLOR: Were all groups of animals sampled? 

T. UMESAO: No, only certain groups. 

A.G. SEARLE: What kind of animal ecologists are 
going on your next trip ? 



A primatologist and an entomologist. 
Where next after your trip through 



T. UMESAO: 

E.H. TAYLOR: 
Thailand? 

T. UMESAO: Not yet determined, 
further trips not yet available. 



Finances for 



59 



PROCEEDINGS OF THE NINTH PACIFIC SCIENCE CONGRESS 



FIELD STUDIES ON THE SOCIAL LIFE OF PRIMATES IN JAPAN 

SYUNZO KAWAMURA 

Osaka City University, Osaka, Japan. 



A group of Japanese ecologists set out in 1948 
a systematic study of the comparative social 
ecology on higher animals. It began with two 
field studies, observations of the semi-wild native 
horses at Point Toi in Kyushyu by Dr. K. Imanisi, 
and of the famous herd of sanctuary deer in 
Nara Park in central Japan by me. We took up 
a characteristic intensive method in these surveys, 
which was a successive observation, long enough 
to make clear the changing phases of the animal 
community, based on accurate recognition and 
discrimination of all the individuals of the 
group. 

In 1950, Dr. Imanisi, Mr. J. Itani and I went to 
Kyushyu for the first investigation of natural 
communities of the Japanese macaque, Macaca 
fuscata fuscata, and since that time we have called 
ourselves Primates Research Group. Prof. 
D. Miyazi (Kyoto Univ.) became the chairman 
of the group, and Dr. K. Imanisi, Mr. N. Ha- 
zama, Mr. M. Kawai, Mr. K. Tokuda, Mr. 
H. Mizuhara, Mr. M. Yamada, Mr. Y. Huruya, 
Mr. S. Maegawa and I its members. This group 
is a branch of the Kyoto School of animal ecology. 

The horses, the deer, the domesticated rabbits 
and the mice were actually in our objects, but our 
primary interest was in Primates, because of their 
phylogenical kinship to human beings. 

The observation of rhesus macaque and 
crab-eating macaque was done in zoo, as well as 
of Japanese macaque in laboratory cage, but 
most of all we have done field studies of the wild 
groups of the native macaque. 

In the course of adopting our intensive method 
with monkeys, we were obliged to go through 
the following three stages : first we pushed through 
forest and bushes of arduous mountains, follow- 
ing after the cautious, cunning and nimble animals. 
General life history with vocal communications 
and some other behavior of the monkeys was 
thus investigated. At the second stage, we 
succeeded to approach the monkeys in close 
distance, after patient endeavour to provide 
them with food. Thus we elaborated the indivi- 
dual discrimination by recognizing the face of 
each animal, and on this basis, we analyzed 
many points of the social functions and forms of 

60 



the community. At the third stage, we stepped 
into a long term observation to see the develop- 
ment of individuals as well as of groups. 

Now we have 16 natural groups, 2 migrated 
natural groups and 2 artificially composed groups 
which are ready for any observation. More 
than half of them have been thoroughly investi- 
gated, and so we are now able to compare group 
after group on many points of social phenomenon. 

i) Mt. Takago (Tiba Pref.); 1 group of 7 groups 
became tamed. 

ii) Okinosima Islet (Aiti Pref.); the Syodo-T 
Group was artificially imigratcd into this 
small islet. (We prepared the Syodo-O 
Group for imigration.) 

iii) Japan Monkey Center (Aiti Pref.); founded 
in 1956. The first journal of primatology, 
"Primates" is published by Japan Monkey 
Center (J.M.C.). 

iv) Arasiyma (Kyoto Pref.); there is 1 tamed 
group. 

v) The Minoo valley (Osaka Pref.); there are 
2 tamed groups. 

vi) Tomogasima Isl. (Wakayama Pref.); 1 arti- 
ficially composed group. 

vii) Tubaki (Wakayama Pref.) ; 1 tamed group, 
viii) Syodo Is. (Kagawa Pref.); 2 tamed groups 
and 1 wild. Another 2 groups were cap- 
tured for imigration. 

ix) Mt. Gagyu(OkayamaPref.); 1 tamed group. 

x) The Taisyaka Valley (Hirosima Pref.); 1 
tamed and 2 wild. 

xi) Sirahama (Ehime Pref.); 1 tamed group. 

xii) Mt. Takasaki (Oita Pref.); 1 tamed group, 
xiii) Kosima Isl. (Miyazaki Pref.); 1 tamed 

group, 
xiv) Point Toi (Miyazaki Pref.); 1 tamed group. 

xv) Yaku Is. (Kagosima Pref.); numerous 
monkeys (M.f. Yakui) live in a wild state. 
They are the important sources of experi- 
mental monkeys in Japan. 

There are another 3 tamed groups in Japan, 
which has not yet been surveyed. 



VOLUME 19 



ZOOLOGY 



The Japanese macaque is endemic to Japan, and 
is distributed over mountainous places in Hon- 
shyu, Sikoku and Kyushyu. We estimate the 
whole population at 50,000-100,000 heads. They 
live in groups of as many as 30-150 heads in 
moderate size, but the group population varies 
from scores to several hundreds. 

They feed on many sorts of vegetable, such as 
fruits, nuts, seeds, root stocks, flowers, buds, 
shoots, leaves, twigs, barks, saps etc. It is 
remarkable that these forest dwellers eat so 
much grass. They are also insect eaters, and some 
of them take land snails. In coastal regions, 
they are known to eat shell-fishes on beach rock. 
They never take meat of any kind, but bird eggs 
are favorite food among some monkey groups. 
There are differences of food habit between 
groups. Babies may learn the foods of their 
group, mainly from their mothers. 

Each group leads its own nomadic life 
within the home range, the extent of which varies 
from within 1 square kilometre to more than 10 
square kilometres. There is no direct correspon- 
dence between the extent of the range and the 
population size. Historical and social factors 
should be seriously considered. 

The pattern of nomadic life is specific to each 
group. Considerable number of groups have 
their centers of nomadism, and from there begin 
circuital movements which repeat fairly often. 
Duration of each nomadic cycle vary from 1 day 
to about 2 weeks. But some groups migrate 4-8 
kilometres seasonally and perform the long cycle 
of nomadism. Another type of cycle occurs in 
some groups which have slow movement day 
after day within their rather vast home range. 
The Takago-A Group belongs to the last type, 
and the Takasaki Group belongs to the first 
type which has a "Base" of nomadism and all 
short cycle of nomadism. 

Although the secondary sex ratio in the group 
generally indicates the rate 1 : 1 or so, we have 
found the socionomic sex ratio varied consid- 
erably between groups. In the Minoo B group, 
there are 9 fertile females against 1 adult male, 
while three groups in Syodo Is. (the Syodo-O.S.T. 
Group) the number of matured male is just the 
same or exceed a little that of mature female. 
The population piramids of the groups are 
generally steady. 

The generalized view of the group organization 
is as follows. The natural community of Japanese 
macaque consists of 2 segments. One of which 
is the internal portion of the group including 



leader males, young and adult females, infants 
and babies. The ordinary males of our term 
form another segment which is the external 
portion of the group. (Fig. 1) Such as resting, 
feeding or slow moving times, these two segments 
usually lay concentrically. But when rapid move- 
ment occurs and the group march in a single 
line, the ordinary males go at the top and the 
rear, placing the internal portion between them. 

The problem of spacial distribution of individ- 
uals in the group has been investigated and 
confirmed in detail. One of the investigation was 
my distribution test on the Kosima Group in 
1954. Here I must refer to the solitary males 
and collective male parties, both of which are the 
male monkeys that have left the maternal group. 
Solitary males are commonly seen in all the 
localities of monkey habitat, while the male 
parties are rarely recorded. The male parties 
are semi-permanent, because they accept new 
partners that come from adjacent groups. Soli- 
tary males often venture off to considerably large 
area, and some of them wander away for ever. 
When the sexual season begins, most of solitary 
males and male parties appear again in the vicinity 
of the group, and some of them apparently are 
born of another group. Solitary males occasion- 
ally return to their original group, and even rise 
to the status of the leader male. 

I have mentioned above that the common 
style of the Japanese macaque community, where 
the leader males and the ordinary males are seen. 
In smaller groups, the population of which is less 
30 heads, we have usually found 1 leader male, 
but in larger group the number of the leader 
males is counted 2 or more. The largest number 
of leaders of a group was 6 heads, which was 
recorded on the Takasaki Group and on the 
Syodo-K Group. Although the population of 
the Takasaki Group has increased from 220 
(1952) to 520 (1957) within these 5 years, the 
number of leader males has decreased from 6 to 4 
during the same period. Many facts are available 
to indicate that there is no direct correspondence 
between the population of the group and the 
number of the leader males, but it may be gener- 
ally concluded that the Japanese monkey reach 
the high equilibrium of having 1 leader male per 
every 20-30 heads. 

The role or function of a typical leader is as 
follows. Usually, the ordinary males are the 
guards of the group, but once a situation became 
serious, the leader male appears in front of the 
enemy, or manages the escape of the whole group. 

61 



PROCEEDINGS OF THE NINTH PACIFIC SCIENCE CONGRESS 



Total 20 Individuals 
External Portion 

"^ *""* % 

Internal Portion 



9b 



i i i 



^ ^ ^ 

i i i 



J Solitary Male 



^ Leader Male $ Chief Female i Infant 
<? Adult Male 9 Adult Female b Baby 



cJ Adoles.Male 

62 Fig. 1. The Kosima Group at Nov. 1952. 



He occasionally climbs up to the top of a tall 
tree, and surveys the conditions or circumstances 
of his groups, then he shakes the tree vigorously 
with loud uttering. This tree shaking behavior 
accompanied by uttering is also performed when 
he gives the starting signal to his monkeys, when 
passing over ridges or when enemy menaces. 

Another remarkable function of the male 
leader is the "controlling." He stops any quarrel 
happening in the group, by attacking or men- 
acing the individual causing the quarrel. 

The leader males and the ordinary males are 
easily distinguished from one another by their 
location and by their function in the group, al- 
though there are exceptions, when the difference 
is obscured by marginal individuals. 

In larger groups, scattered over the internal 
portion, the leader males have a good team work 
under a linear dominance rank system. Each 
leader male has his own role about this poliarchal 
team work, but some of them have no important 
job in their team. 

In the case of the Syodo-K Group, the division 
of labour among the leader males was as follows. 

The first male : he is old and retired from serious 
job. 

The second male : he did actual leading service. 
He was the axis of the group, but a respected 
first male as well. 



VOLUME 19 _ ZOOLOGY 

The third male: he is next to the second male 

in leading service. 
The fourth and the fifth male: they were the 

complemental leaders. 
The sixth : he has the special job in giving alarm 

and piloting. 

There are seldom fights or duel for dominancy 
in the natural group of Japanese monkey, and so 
old leaders decline slowly to the declining leader 
status. It seems that there is no sudden change, 
through this process. In the Syodo-S group, 
the oldest male that is estimated about 30 years 
old still holds the predominant position of leader. 
Although he can no longer climb trees well. 

The ordinary males are the young or adult 
males who had been rejected from entering the 
internal portion by leaders and females. But 
males go out to the external portion rather natu- 
rally when they are 3-4 years old. 

In some groups there are marginal individuals 
between the leader and the ordinary male. They 
are the adult and the adolescent center male of 
pur term, and they are tolerated by leaders to live 
in the internal portion. There is a remarkable 
difference between the group that has the center 
male and the group that has not, on the design 
of group construction. In other words, there 
is a variety on group integration. Some of the 
center males were sons of higher rank females. 



Bef. 1948 



2J 3J 101? 



1948 4J 



Q029) 
Dead 



105V 
1st Year 



107s 



1949 
1950 
1951 
1952 
1953 

1954 
1955 
1956 1179 



6J 
Joined 



103? 



1049 



109^ 1109 9J 




(The behavior trait first appeared in this Year.) 

T" 



1159 



1169 



1139 
4 



8cT 



1129 



1149 



Fig. 2. The "Potato- Washing-Behavior" originated from an infant female in 1953, and spreaded slowly but 
steadily over a half of the Kosima Group in three years. I trace here its process on the lineage of the group. 

63 



PROCEEDINGS OF THE NINTH PACIFIC SCIENCE CONGRESS 



There are a few females who have a special 
contact with the predominant leader male. By 
this she wins the highest position among females 
in dominancy, we call her the chief female. 
The typical chief female was found in the Kosima 
Group and in the Minoo-A, B Group. Social 
relation between the predominant leader and the 
chief female continues all year round, including 
non sexual seasons. The chief female does a part 
of the role of the leader male, for instance, the 
tree shaking and the controlling. 

The population, the socionomic sex ratio and 
members of each status of five groups are shown 
on Table 1. The declining leader is not seen in 
these 5 groups, but he was in the Taisyaku-A 
Groups. Next there is the intergroup relation- 
ships among groups. 

In Syodo Is. there were 5 groups in the central 
hill. They seemed to segregate their habitation 
pretty well, although there were some overlapping 
portion between them. 

I think they settled their borders according to 
the physiognomy of mountains, and their own 
preference. For instance, no one of the Syodo- 
O group ever went westward beyond a shallow 
stream of the upper Tatibana River, whereas they 
used to proceed over more difficult valleys. 

In Takago district, a more complicated rela- 
tionship was found. Some of borders are more 



sociologically settled than Syodo Is. They seem 
to avoid meeting each other but, lesser groups 
avoid other groups more often than the larger 
ones. 

The next problem is that how a new habit or 
custom is introduced into the group. On this 
problem the Japanese monkeys afford some 
interesting data of sub-human culture. 

We observed a process of a social learning in 
the Minoo-B group. All the members of the 
group learned of wheat as a food from a young- 
adult male, Nasio, who recently returned from 
a male party which had the habit of wheat eating. 
They completed this learning in 4 hours. 

Fig. 2 shows the "Potato- Washing-Behavior" 
that originated from an infant female in 1953, 
and spread slowly but steadily over half of the 
Kosima Group in three years. The process on 
the lineage of the group, can be traced. 

Each group of Japanese macaque has so many 
specific behavioral types in selecting its food, 
in leading its nomadism, in organizing its 
community, etc. Vocalization and some other 
sign behaviors are also specific to some groups. 
It is believed that part of them were acquired or 
learned by the monkeys and later became tradi- 
tions of the group and then these are their 
culture. 



Table 1. 
Population, Socionomic Sex Ratio and Members of Each Status of 5 Representative Groups. 





1952 


1956 


1957 


1955 


1957 


1957 


1953 


1957 


Population 


20 


28 


62 


67 


98 


150-160 


ab.260 


ab.520 


Socionomic Sex Ratio (^) 


1.25 


1.13 


1.42 


2.60 


2.33 


5.00-5.20 


2.50 


1.69 


Leader Male m 


1 


1 


2 


2 


3 


6 


6 


4 


f Adult 






1 






i 






Center M. | Ado1escent 








1 


2 


I 







. 


Declined Leader M. 


. , 

















, 





~ ,. ,, [Adult 
Ordinary M.( Ado , escent 


2 
1 


3 
4 


3 
5 


3 
3 


3 
9 


3 


J30 


85 


Elder Infant M. 


1 


4 


4 


10 


10 


20-25 


30 


40 


Chief Female 


1 


1 





1 


1 











~ ,. _, ( Adult 
Ordinary F. | Adolescent 


4 


4 
4 


13 

4 


13 
12 


24 
10 


35-37 
15 


60 
30 


130 
20 


Elder Infant F. 


1 





2 


5 


8 


13-15 


30 


40 


Younger Intant (M. &F.) 


6 


2 


17 


10 


14 


26 


30 


120 


Baby (M.&F.) 


3 


5 


10 


6 


15 


31 


45 


86 


Semi Solitary Male 
Solitary M. 


1 


2 


2 


1 


2 
1 


2 


il 


ab.10 


Collective M. 











10 


5 


14 








64 



VOLUME 19 ZOOLOGY 



DISCUSSION 

N.A. MEINKOTH: Do the monkeys pay attention to will contribute to our understanding of comparative 
the observer? behavior. 

s. KAWAMURA: Yes, but these can be distinguished. Dr. Coolidge then commented on the nature of 

H.J. COOLIDGE: Commends the work done at the the Institute and primate studies in progress in 
"Private Institute" in Japan. This is rather unique, and Japan. 



65 



PROCEEDINGS OF THE NINTH PACIFIC SCIENCE CONGRESS 



CYCLIC CHANGES OF MOUSE EPIDERMAL CELLULAR POPULATION 
IN CORRELATION WITH THE HAIR FOLLICULAR ACTIVITY 

HSU-MU LIANG 

Biomorphic Department, National Defence Medical Center, and Zoological 
Institute, Academia Sinica, Taipei, Taiwan, Republic of China. 



INTRODUCTION 

Pinkus (1927) held the concept that replace- 
ment of the desquamating and keratinized cells 
in the epidermis was by mitotic division of the 
basal cells. Storey and Leblond (1951) found 
that this process was at such a rate that the 
neoformation of cells balanced exactly the cell 
loss due to desquamation. Therefore the assump- 
tion is that the number of cells in epidermis 
remains constant. In other words, the epidermis 
is a "steady system" in regards to its cellular 
content. 

On the contrary, one of the epidermal appen- 
dages, the hair follicles, undergo a wave-like 
pattern of degenerating and regenerating phases 
of growth. This cyclic phenomenon is well known 
to exist in laboratory animals by many investi- 
gators (Dry, 1926; Butcher, '34, '51; David, 
'34; Schwanitz, '38; Lubnow, '39; Kaliss, '42; 
Taylor, '49; Walbach, '51; Chase et al., '51; 
Andreasen, '53; and Liang and Cowdry, '54). 
In association with different phases of hair folli- 
cular cycles, changes of epidermal thickness were 
reported (Andreasen, '53; Chase et al., '53; and 
Liang et al. 9 '54). 

However, the total cell counts and the numeri- 
cal proportions of different kinds of cells in the 
normal epidermis in correlation with different 
phases of the hair follicular activities are still 
wanting. This information is important for the 
thorough understanding of skin under normal 
and experimental conditions. 

The established fact that plucking of club 
hairs will initiate growth of the succeeding hair 
generation (Collins, '18; David, '34; Schwanitz, 
'38; and Chase, '46, '49a, b) makes it possible 
to control hair follicular cycles which can be 
divided into growing (Anagen), degenerating 
(Catagen) and resting (Telogen) stages (Dry, 
'26; and Chase et al., '51). 

MATERIAL AND METHODS 

In the present experiment 50 normal female 
mice of C57 black strain were used. Pieces of 

66 



skin from the dorsum of known phases of hair 
follicular growth were excised. Half of the 
skin from each animal was fixed, embedded in 
paraffin, cut in serial sections both cross-wise and 
longitudinally, and stained with hematoxylin 
and eosin. The other half was treated with cold 
acetic acid (Liang, '47), separated into epidermis 
and dermis, stained with hematoxylin, and 
prepared into whole mounts. The thickness of 
each epidermis was measured with an eye-piece 
micrometer under oil immersion elective. The 
total epidermal nuclear counts per mm 2 and the 
population of different kinds of cells were 
estimated according to Abercrombie's formula 
(Abercrombie, '46). 

RESULTS AND CONCLUSIONS 

It was found that the epidermis was thickest 
(31.06ji) during early anagen phase. The thick- 
ness increased abruptly from telogen to early 
anagen, and then dropped in late anagen phase 
during which it was the thinest (11.48|i). From 
then on the thickness of epidermis remained with 
little change passing through the telogen stage 
(12.28 ,1). 

Pari passu with changes of epidermal thickness, 
the number of the total epidermal nuclear counts 
per mm 2 changed accordingly. It was greatest 
(21,600) during early anagen and then dropped 
gradually in late anagen when the nuclear count 
was the least (13,700). From now on it increased 
through catagen (14,100) to telogen (15,000) 
which then shot abruptly again to its peak at 
early anagen. 

The numerical proportions of different cells 
also fluctuated. The most obvious change 
occurred in the granular and spinous layers in 
which the cells in the former increased 150%, 
and in the latter 90%, during early anagen when 
compared with those of the telogen. From 
then on, both granular and spinous cells dropped 
rapidly even to "sub-normal" level when late 
anagen was reached. On the other hand the 
basal cells remained with little change through- 
out the whole cycle, but increased slightly (13%) 



VOLUME 19 



ZOOLOGY 



during early anagen and then returned to telogen 
at mid-anagen. 

The results mentioned above were expressed 
by the following tables, and were counter-checked 
by whole mount studies of both epidermis and 
dermis. 

From what had been observed in this study, 



it showed that the normal condition of mouse 
epidermis is not a "steady system" but changes 
according to hair follicular cycle, and the replace- 
ment of desquamating cells is carried out, most 
likely, by spinous cells instead of basal cells, 
as indicated by the constancy in the number of 
basal cells and the large fluctuation of spinous 
cells. 



Table 1. 
Nuclear Counts and Nuclear Diameter. 



Stage or Time 


Nuclear counts per mm 2 


Diameter (micron) of 


basal 
cell 
nuclei 


spinous 
cell 
nuclei 


all inter- 
mitotic 
nuclei 


granular 
cell 
nuclei 


all 
nuclei 


basal 
nuclei 


spinous 
nuclei 


granular 
nuclei 


Telogen (control) 


10,000 


3,300 


13,300 


1,600 


14,900 


6.23 


7.96 


8.13 


Anagen II ( 3 days) 


11,300 


6,300 


17,600 


4,000 


21,600 


6.84 


8.08 


8.44 


Anagen IV ( 6 days) 


10,600 


4,900 


15,500 


3,000 


18,500 


6.77 


8.01 


8.05 


Anagen VI ( 9 days) 


10,200 


4,200 


14,400 


2,000 


16,400 


6.43 


7.44 


7.85 


Anagen VI (12 days) 


9,500 


3,400 


12,900 


1,600 


14,500 


6.80 


8.15 


8.39 
~~8J25~ 


Anagen VI (15 days) 


9,700 


2,500 


12,200 


1,500 


13,700 


6.45 


7.77 


Catagen (18 days) 


9,800 


2,900 


12,700 


1,400 


14,100 


6.35 


8.02 


8.23 


Telogen (21 days) 


10,100 


3,300 


13,400 


1,600 


15,000 


6.17 


7.86 


8.05 



Table 2. 
Thickness (micron) of Epidermis. 



Stage or Time 


Intermitotic layer 


Granular layer 


Hornified layer 


Whole epidermis 


Telogen (control) 


9.35 


1.80 


1.13 


12.28 


Anagen II ( 3 days) 


17.51 


8.12 


5.43 


31.06 


Anagen IV ( 6 days) 


13.20 


4.04 


3.50 


20.74 


Anagen VI ( 9 days) 


11.72 


2.63 


2.96 


17.31 


Anagen VI (12 days) 


9.88 


2.41 


2.42 


14.71 


Anagen VI (15 days) 


8.30 


1.61 


1.57 


11.48 


Catagen (18 days) 


8.68 


1.56 


1.35 


11.59 


Telogen (21 days) 


9.38 


1.93 


1.19 


12.50 



DISCUSSION 



A.G. SEARLE: What happens if you pluck hairs at the 
anagen rather than the telogen stage? 
H.M, LIANG : Plucking of the club hair is to stimulate 



the growth of the new hair germs, while the hair germ&have 
already been stimulated to grow through their natural 
cause, further plucking of club hair will cause little effect. 

67 



PROCEEDINGS OF THE NINTH PACIFIC SCIENCE CONGRESS 



ZOOLOGICAL EXPLORATION OF NETHERLANDS NEW GUINEA 

L. D. BRONGERSMA 

Rijksmuseum van Natuurlijke Historic t Leiden, Netherlands. 



After Vasco da Gama discovered the sea route 
to the Indies in 1498, the Portuguese extended 
their voyages far to the east, and in 1511 they 
reached the Moluccas; they were soon followed 
by the Spaniards. In 1526 De Menezes visited 
some islands to the north of Geelvink Bay 
(probably the islands of Biak and Noemfoor), 
and in 1545 Ortiz de Retes reached the coast of 
the New Guinean mainland; in 1606 Luis Vdez 
de Torres proved that New Guinea is an island. 
Dutch explorers also found their way to New 
Guinea, and sailing along the south coast in 
1623 Carstensz sighted the snow-covered tops of 
the central mountain range. Many other voyages 
were made to New Guinea in the 17th and 18th 
centuries, but none of them was planned for 
scientific research. Nevertheless, the first infor- 
mation about the fauna reached Europe through 
these explorers, because they brought home 
specimens as souvenirs (e.g., the plumage of 
Birds of Paradise). It took many years before 
naturalists visited New Guinea or the adjacent 
islands. Sonnerat, the first of these naturalists, 
was evidently possessed of a lively imagination, 
which he displayed in a book published in 1776 
entitled "Voyage & la Nouvelle Guinfee". He 
did not reach New Guinea itself, but he visited 
the island of Gebe. From Papuans who crossed 
from Salawatti, he received a number of bird 
skins, and thus he could describe and figure 
various species unknown until then. Probably 
to add to the "value" of his book, Sonnerat 
included some birds that do not occur in New 
Guinea at all, viz., three specimens of penguins. 
It is due to this fraud that an Antarctic penguin 
has been named Pygoscelis papua Forster. 

More serious research started in the 19th 
century. Several French expeditions visited 
New Guinea on their voyages, and one is still 
reminded of those taking part (Freycinet, D'Ur- 
ville, Quoy & Gaimard, Hombron & Jacquinot) 
by many geographical, zoological, and botanical 
names. The first Dutch expedition to New 
Guinea in which naturalists took part visited the 
south coast in 1828 in H. Neth. M. corvette 
"Triton." In 1858 an expedition reconnoitred . 
part of the south coast, and the north coast to 
Humboldt Bay. In later years C.B.H. von 

68 



Rosenberg and H. A. Bernstein visited New 
Guinea and neighbouring islands to make 
zoological collections for the Rijksmuseum van 
Natuurlijke Historic at Leiden. Besides these 
collectors, who were in the service of the Ne- 
therlands Government, many travellers from 
other countries collected in New Guinea, viz., 
Alfred Russel Wallace, Beccari, D'Albertis, 
Meyer, Maindron, Raffray, Laglaise, etc. How- 
ever, the exploration was limited mainly to the 
coastal areas. 

The 20th century began with intensified 
activity, and a number of expeditions penetrated 
into the interior. In 1903 a Dutch expedition 
visited the north coast; three expeditions to the 
regions south of the central mountain range 
followed in 1907, 1909-1910, and 1913, and in 
1920-1921 an expedition started from the north 
coast to penetrate to the Nassau Mts. and to 
Mt. Wilhelmina; a Netherlands-German border 
expedition took place in 1910. Two British 
expeditions visited the south in 1910- 191 1 (British 
Ornithologists' Union Expedition), and in 1912- 
1913 (Wollaston Expedition); a Netherlands- 
American expedition went to the Nassau Mts. 
in 1926. In all of these expeditions zoological 
collections were brought together which have 
proved very important in furthering our knowledge 
of the fauna. Moreover, the number of travellers 
individually made journeys to New Guinea, 
amongst others Miss L. E. Cheesman, who made 
important herpetological and entomological 
collections for the British Museum (Natural 
History). 

In earlier days the problem of transportation 
was a handicap to all collectors. Where bearers 
had to be used, the equipment, and hence the 
collections, had to be limited. Better conditions 
were arrived at when air transport became 
available. The American-Netherlands Archbold 
expedition (1938-1939) made successful use of a 
flying boat. The expedition of the Royal Nether- 
lands Geographical Society to the Wissel Lakes 
(1939) received transportation from the Royal 
Netherlands Naval Air Service, enabling it to 
bring extensive equipment into the field, and 
large collections were taken home. 



VOLUME 19 



ZOOLOGY 



The second world war stopped all scientific 
exploration in New Guinea, except that some 
members of the U.S. Forces made collections in 
the area. In 1948 the exploration was resumed 
when a Netherlands-Swedish expedition visited 
the island of Misool and the Vogelkop Peninsula. 
A number of traveller went individually to New 
Guinea; some of them to make collections for 
museums, others to obtain living Birds of Paradise 
for zoological gardens. The Swedish traveller 
Sten Bergman deserves special mention in this 
connexion for the interesting reports he has 
published on the courtship display of various 
species of Birds of Paradise; recently Bergman 
has succeeded in breeding King Birds of Paradise 
in captivity. 

If we compare our present-day knowledge of 
the fauna of New Guinea to that of some sixty 
years ago, it is evident that much progress has 
been made, but it is equally clear that still more 
remains to be done. Aerial photography may fill 
up the large gaps once existing in our maps, 
but very large parts of the country have still to 
be explored from the ground. The central moun- 
tain range is difficult of access, and well-equipped 
expeditions will be necessary to penetrate into 
this part of the island. However, in many 
places in the lowlands and in the mountains the 
government and missionaries have settled, and 
these settlements offer good opportunities for 
individual collectors. The zoological exploration 
of the surroundings of these areas must not be 
delayed too long, because more and more of the 
land becomes cultivated, and this will greatly 
influence the composition of the fauna. Moreover, 
the zoological exploration may be of benefit to 
agriculture, fishery research, etc. With these 
arguments in mind the Rijksmuseum van Natuur- 
lijke Historic, Leiden, made plans to intensify 
research by sending out zoologists, each of which 
a specialist in some groups of animals. It is 
important for the specialist to bring together 
the collections himself; he receives the specimens 
when they are still fresh, and the colours are not 
yet affected by drying or by preservation fluids; 
he may also be able to obtain information about 
the environment in which the species live, etc. 

The first to visit Netherlands New Guinea 
under this scheme was the author of this report, 
who was sent out with one assistant in 1952. The 
funds for the voyage were provided by contribu- 
tions from several scientific societies, private 
persons, and from industrial concerns. TTie full 
support of the Government of Netherlands New 
Guinea was obtained. Most liberal support was 



also given by the Royal Netherlands Navy. Only 
this help made it possible to visit many interesting 
places which the ordinary traveller never reaches 
from lack of transportation. Hospitality was 
also received from government officials and 
private persons. The main object was to assem- 
ble a collection of reptiles and amphibians, but 
attention was paid to other groups of animals 
as well. For a clear picture of geographical 
variability extensive series were needed from 
various localities, and the inhabitants did all 
they could to provide us with an ample supply. 
After a stay of about six months more than two 
thousand reptiles and amphibians were sent 
home for further study; particular attention was 
paid to the distribution and variability of poi- 
sonous snakes, the animals preyed upon, the 
number of young, etc. As this trip proved to be 
successful means and ways were sought for to 
continue the exploration in following years. 

When the American forces occupied the 
islands of Biak and Owi towards the end of the 
Second World War, a great many cases of scrub 
typhus were reported. Although there was no 
such outbreak among the Netherlands forces 
that came to these islands, the possibility of a 
new outbreak remained. It was of vital interest 
to the medical service of the Royal Netherlands 
Navy to obtain data on the distribution of the 
mites (Trombiculidae) that carry the disease. Dr. 
L. van der Hammen, acarologist of the Leiden 
Museum, travelled to New Guinea for this purpose, 
and with full support of naval surgeons he 
studied various suspected areas. A report on the 
mites, their habitats, repellents, etc., was pub- 
lished in 1956. This research will have to be 
extended to a study of the animal hosts that 
serve as the scrub typhus reservoir. Dr. Van 
der Hammen also made extensive collections of 
Moss Mites (Oribatei), a group to which but 
little attention had been paid by previous collec- 
tors. 

A further step was taken when the Govern- 
ment invited Dr. M. Boeseman to make a survey 
of the fish in several lakes and rivers (1954- 1955). 
At the same time Dr. L. B. Holthuis travelled to 
Netherlands New Guinea to study the Crustacea 
of this region; the present author went out a 
second time to continue his studies on reptiles 
and amphibians; the trip was made possible by a 
grant from the Netherlands Organisation of 
Pure Research. Again the Royal Netherlands 
Navy gave liberal support both as regards hospi- 
tality and transportation. During a stay of 
about seven months many interesting places 

69 



PROCEEDINGS OF THE NINTH PACIFIC SCIENCE CONGRESS 



were visited: the surroundings of Hollandia, 
Tami River, Lake Sentani, and the Nimboran 
area in the north-east of the Netherlands terri- 
tory; the islands of Biak, Noemfoor, and Japen 
in Geelvink Bay; the Wissel Lakes in the Central 
Mountains; Ajamaroe, Aitinjo, and Manokwari 
in the Vogelkop Peninsula; Sorong and Misool 
Id. in the west; Fakfak in the south-west; Merauke 
and Tanah Merah in the south. About two 
thousand reptiles and amphibians, ten thousand 
fishes, and thirty thousand Crustacea were 
collected. The studies on the fish fauna by Dr. 
Boeseman, and those on Crustacea by Dr. 
Holthuis will help much to obtain a more com- 
plete picture of the composition of the fresh- 
water fauna; these studies will also be of value to 
future fishery research, and hence to the food 
supply of the inhabitants. A remarkable feature 
of the fauna of New Guinea is the penetration of 
many marine forms into freshwater. This 
applies not only to the fish fauna (e.g., sharks in 
Lake Jamoer; Carangidae in Lake Sentani; etc.) 
but also to the sea-snakes. The sea-snake 
Enhydnna schistosa (Daud.) is fairly common in 
the Digoel River near Tanah Merah, 450 km. 
from the mouth of the river. Crayfish of the 
family Parastacidae occur only in freshwater 
basins that drain to the south; they are found in 
the central mountains (e.g., in the Wissel Lakes), 
in the southern lowlands, in the Vogelkop 
Peninsula (e. g., the lakes near Ajamaroe and 
Aitnijo), and on the island of Misool. Where 
fish are abundant (Lake Jamoer) Parastacidae are 
scarce, but in waters without fish (Wissel Lakes) 
or with a relatively poor fish fauna (lakes near 
Ajamaroe and Aitinjo, brooks flowing into Lake 
Jamoer) Parastacidae are abundant. To what 
extent crayfish and fish exclude one another will 
have to be studied in more detail, especially with 
regard to plans to introduce fish into waters where 
crayfish form as yet the only source of animal 
proteins for the local inhabitants (Wissel Lakes). 

An agreeable consequence of the three trips 
made in recent years is the interest shown by 
persons living in New Guinea; several people 
have started collecting specimens for the museum, 
and many valuable data have been procured by 
them. In this way we received specimens of the 
strikingly coloured python (Liasis boeleni Bron- 
gersma) of the Wissel Lakes area, and recently 
photographs showed that the Longbeaked Spiny 
Ant-eater (Zaglossus bruynii Peters & Doria) 
occurs in this region. In 1910 M. Weber reported 
upon the occurrence of Sderopages leichardti 
Gtinther in the Digoel River; his report was 

70 



based on a photograph received from Mr. J.M. 
Dumas; previously the species was known only 
from Queensland. Remarkably enough attempts 
made at the time to obtain specimens for further 
study all failed, and when Dr. Boeseman and 
I visited the Digoel River in 1955 we did not 
succeed in securing this fish. However, within a 
year's time two adult specimens and two juveniles 
reached our museum. 

It is a long established fact that the fauna of 
New Guinea greatly resembles that of Australia, 
but that it differs widely from the fauna of Asia. 
This difference made a deep impression on the 
zoologists who in the 19th century travelled from 
Asia to New Guinea (e.g., S. Miiller, A. R. 
Wallace), and many have been the discussions on 
the boundary between the Oriental and Australian 
regions of zoogeography. These problems do not 
need to be discussed here. Of more interest at 
the present time is the distribution of the fauna 
of New Guinea itself and of the adjacent islands. 
In 1936 Stresemann discussed the distribution of 
birds; this author showed that numerous species 
are represented by different subspecies north and 
south of the central mountains; sometimes the 
northern subspecies has penetrated to the west 
into the Vogelkop Peninsula, in other instances 
it is the southern subspecies that occurs there. 
The Crowned Pigeons (genus Gourd) are 
represented by three species: one species in the 
Vogelkop Peninsula, one south of the mountains, 
and one north of the range. Little has been 
mentioned in literature about the distribution of 
reptiles and amphibians, although these groups 
also give evidence of the possibility of dividing 
Netherlands New Guinea into at least five faunal 
areas: the Vogelkop Peninsula in the west, the 
lowlands north of the central mountains, the 
lowlands south of the range, the area around 
Merauke in the south, and the central mountain 
range. The Vogelkop Peninsula Harbours several 
species of amphibians and reptiles that also occur 
in the Moluccas, but that are absent from the 
rest of New Guinea, e.g., the tree frog Nycti- 
mystes amboinensis (Horst), the snake Natrix 
elongata (Jan), and the lizard Hydrosaurus 
amboinensis (Schloss.). The lowlands south of 
the mountains and the waters draining to the 
south coast harbour many species not found in 
the north, nor in the Vogelkop Peninsula, e.g., the 
freshwater turtle Carettochelys insculpta Ramsay, 
which occurs in Lake Jamoer and in the southern 
rivers (Setekwa River, Lorentz River, Digoel 
River, etc.). The snakes of the genus Pseudechis 
are only found in the south, and in the Netherlands 



VOLUME 19 



territory this probably also applies to the marsh 
tortoises of the genus Chelodina. Among the 
species of the genus Emydura this applies to 
Emydura subglobosa (Krefft), which is abundant 
at Lake Jamoer, and further to the south-east, 
e.g., at the Koembe River. This Emydura spe- 
cies is remarkable for its sloughing; the scutes of 
carapace and plastron peel off, several scutes 
together; moreover, this tortoise is noteworthy 
by producing a soft whistling sound (males only ?). 
Emydura novae-guineae (Meyer) has a much 
wider distribution; it occurs north and south of 
the mountain range, in the Vogelkop Peninsula, 
and on the island of Waigeo. The area surround- 
ing Merauke differs faunistically from the other 
lowlands. Here the Frilled Lizard (Chlamydo- 
saurus kingi Gray) is found; the Death Adder 
is represented by a distinct subspecies, Acantho- 
phts antarcticus rugosus Loveridge, and another 
snake (Natrix Mairii Gray) is represented by a 
form that comes close to that living in Australia. 
The absence of the Death Adder from the greater 
part of the Vogelkop Peninsula, and from the 
islands of Salawatti and Misool is interesting, 
as the species occurs farther to the west in the 
Moluccas (Ceram, Haruku, Obi). The New 
Guinean marsh crocodile (Crocodylus novae- 
guineae Schmidt) was described from the Sepik 
River in the Territory of New Guinea; later it 
was recorded from the neighbourhood of Port 
Moresby, and now it has been found in several 
localities in Netherlands New Guinea: Tami 
River, Lake Sentani, Lake Jamoer, and the 
Digoel River. Probably this species occurs in all 
lowlands, except in the Vogelkop Peninsula. 

A matter of special interest is the forming of 
subspecies on the mainland of New Guinea, and 
on the adjacent islands. While all specimens 
of Liasis amethistinus (Schn.) from the mainland 
apparently belong to one and the same form, 
the island of Biak harbours a distinct subspecies, 
while other subspecies occur in the Moluccas, the 
Bismarck Archipelago, and in North Australia. 
The study of the subspecies in New Guinean 
reptiles is still in the initial stage, but the large 
series of many species recently acquired will 
offer possibilities for intensifying this part of 



ZOOLOGY 

research. 

A continuation of the zoological exploration 
will make it possible to obtain a better picture of 
the distribution of many species, and of the faunai 
differences from area to area. The study of the 
habits of economically important species (e.g., of 
the crocodiles: Crocodylus porosus Schn. and 
Crocodylus novae-guineae Schmidt) is of impor- 
tance to prevent extermination; measures have 
already been taken to protect these species to some 
effect, but more knowledge of the life history 
will enable the Government to make the protec- 
tion more effective still. The study of species 
introduced into New Guinea (e.g., deer) is of 
importance as it may give us information about 
the deleterious effects of such introductions. 

An important step to the further exploration 
of the central mountain range will be taken in 
1958 when an expedition will go to the Star 
Mts., an area not yet visited by scientists. Various 
fields of research will be represented, among 
them zoology. This expedition will enlarge the 
knowledge of the mountain fauna obtained by 
two previous expedition in areas farther to the 
west (Wissel Lakes; Lake Habbema and Mt. 
Wilhelmina) ; it will be largely indepent of bearers, 
which use up much of the supplies they carry. 
An air-strip has been constructed in the valley 
of the River Sibil at 1200 m. above sea-level; 
this will make it possible to fly in personnel and 
supplies, and to take out large collections. Ex- 
ploration groups will proceed into the mountains 
on foot, but they will be supplied from the air 
by helicopter. 

The remarkable fauna, and the great diversity 
in environment make New Guinea an ideal 
country for zoological research. It reaches from 
the hot tropical lowlands to the snow-covered 
mountains, from areas with a well marked dry 
season and with a relatively low annual rainfall 
(Merauke, 1530 mm.) to places with an annual 
rainfall of 6434 mm. (Ninati at the southern foot 
of the mountains), from dense forests to open 
grasslands and tree-less mountains. This diversity 
in climate and vegetation brings along a diversity 
of the fauna well worth studying. 



DISCUSSION 



Dr. Taylor asked how Dr. Brongersma was able to 
obtain the use of three modern ram jet helicopters for 
this expedition. Dr. Brongersma replied that the navy 
and private concerns were interested in this work for 
various reasons, and underwrote the cost. Further, 
knowing the right naval officers facilitated matters greatly. 



Dr. Mead asked about the personal dangers of canabal- 
istic local inhabitants. Dr. borngersma said that while 
such danger exists, his own experiences proved the local 
inhabitants pleasant, friendly and amused, and quite 
willing to barter specimens for fish hooks and razor 
blades. 

71 



PROCEEDINGS OF THE NINTH PACIFIC SCIENCE CONGRESS 



GEOGRAPHY AND SYSTEMATIC RESEARCHt 

EUGENE MUNROE 

Principal Entomologist, Insects Systematlcs and Biological Control Unit, Ottawa, Canada. 



The importance of geography in the subject 
matter of systematics is well known, and I do not 
propose to discuss it here. This paper deals 
with the practical effects of geography on syste- 
matic research, a subject on which I have formed 
some opinions in the course of a number of years 
of work on a variety of faunas. 

Geography affects the planning of systematic 
research in several ways. These depend basically 
on the spatial and political relations of the 
worker to the habitats of the groups he wishes to 
study, to the sites of important collections, 
including those in which type specimens are 
housed, and of libraries and working facilities, 
and to sources of financial support for the work. 

From many standpoints the simplest kind of 
taxonomic project to organize is the local, 
faunistic one. Worker, facilities, funds and 
fauna are all in close proximity and problems of 
finance and transport are consequently mini- 
mized. It is not surprising that the great majority 
of projects actually undertaken are of this type. 
Even here, however, geographic problems arise. 
Faunistic work is geographically concentrated, 
but the tendency is for larger groups to be studied, 
so that the taxonomic knowledge of the worker 
tends to be attenuated. He is consequently at the 
mercy of outside specialists or of his own incom- 
plete knowledge for correlation with other faunas 
and the broader taxonomic framework of each 
group. Years ago Rothschild and Jordan in 
their comprehensive studies of swallowtail butter- 
flies noted that the existence of local lists was 
often more of a hindrance than a help, because of 
the constant necessity for checking out-of-date 
identifications from a variety of sources, often 
inadequately correlated by the non-specialist 
author. Correspondence with specialist identi- 
fiers involves the difficulty of locating suitable 
specialists to begin with, and of keeping abreast 
with and harmonizing their divergent views. In 
many groups careful faunistic work necessarily 
involves the study of foreign collections, either 
because important collections of the fauna are 
kept in foreign institutions, or because the type 
specimens of many of the species are in foreign 



countries. In such cases the student must travel 
abroad even if the fauna of the country concerned 
is not directly related to the one he is studying. 

With a primarily taxonomic rather than 
faunistic approach, projects tend to become 
global in scope. Practical geographic problems 
become acute, though this is somewhat offset 
by the technical advantages inherent in a balanced 
study. It is not surprising that projects of this 
kind have always been in the minority. Unfor- 
tunately, the proportion has tended to decrease 
with the modern decrease in private or indepen- 
dent sources of support. The practical obstacles 
in the way of work on a group from a world- wide 
standpoint are obvious. First, the assembly 
of material presents formidable problems. Speci- 
mens can be bought from some places, exchanged 
from others, and borrowed from yet others; 
these sources can sometimes be supplemented 
by expeditions to regions of particular interest. 
However, most of these arrangements are costly 
and all are time-consuming. The most important 
difficulty in the assembly of really representative 
material is not money even a modest annual 
expenditure over a long period of time will bring 
surprising returns or the generosity and patience 
of collectors and curators both are very great 
but the sheer expenditure of time in correspon- 
dence, and in labellings, preparing, arranging, 
packing and shipping specimens. Secondly, 
even when large collections have been assembled 
and satisfactory taxonomic concepts have been 
formed, the correct application of names requires 
the examination of type specimens, which may 
be scattered in a variety of collections in a number 
of countries. To a large and increasing extent 
types are being immobilized by institutional 
policy. It is of course possible, if time and money 
are available, to go to see types, but even so one 
must depend on notes, sketches or photographs, 
and it is impossible to examine the types in 
conjunction with the representative series which 
may have taken so much time to collect. Thirdly, 
funds for the prosecution and publication of 
large taxonomic studies nowadays come to an 
increasing extent from governmental sources, 



t Contribution No. 3773, Entomology Division, Science Service, Canada Department of Agriculture. 
72 



VOLUME 19 



ZOOLOGY 



and governments tend to be interested primarily 
in work applicable directly within the political 
boundaries under their jurisdiction. Work of 
broader scope has less immediate appeal to 
them, and is correspondingly harder to initiate 
or justify. 

I think it will be agreed that in spite of these 
practical disadvantages the broad taxonomic 
study is a desirable and indeed an essential 
complement to the narrow faunistic one. Syste- 
matists have therefore a responsibility to under- 
take constructive measures to overcome the 
difficulties in its way. Problems of material, 
though important, are perhaps in general the 
easiest to overcome. For almost all broad taxo- 
nomic projects there is already in collections an 
abundance of material if only it can be assembled 
it is the specialized geographic or microtaxonomic 
study that is likely to need material in excess of 
the available supply. The co-operation of col- 
leagues is very readily obtained, and it is only 
rarely that unrealistic individual or institutional 
policies stand in the way of the assembly of 
material for worthwhile studies. 

A curious phenomenon that sometimes inter- 
feres with the free flow of material, one that 
is in a way symptomatic of our times, is what 
may be called taxonomic nationalism. This is 
the view that the fauna of a particular political 
area should be preseved for collection or even 
for study by nationals of that area. I think it is 
fair to say that this restrictive attitude seems to 
be most prevalent in countries where taxonomic 
work has for one reason or another lagged in the 
past and where a rising generation of active 
workers views with regret the time and oppor- 
tunities that have been lost. I can say this 
without prejudice as my own country has not 
always been free of taxonomic nationalism. 
Although the local concentration of material 
pertaining to a geographic area is a valuable and 
desirable thing, this should be brought about 
by positive and flexible means, not by negative 
and rigid ones. The overall scientific objective 
must always be to increase the amount and 
availability of human knowledge. Attempts to 
secure local advantage by the restriction of 
information and facilities almost always result 
in more loss than gain, because of the general 
slowing of progress in the field of research con- 
cerned, and because purely local studies must 
invariably contain elements of error and bias 
that could be eliminated by taking a broader 
basis or by consultation and collaboration with 
outsiders. 



Taxonomic nationalism often means that 
collections are preserved in places inconvenient 
from the standpoint of the main centres of 
research on the groups concerned, or indeed from 
the standpoint of safe preservation over long 
periods of time. Indeed the location of collec- 
tions presents very special problems, not wholly 
bound up with nationalism. It is true that 
almost any place, whatever its climate, can by 
the aid of modern techniques be made safe for 
the preservation of specimens. In unfavourable 
climates, however, especially in the wet tropics, 
safety requires much more rigid and frequent 
measures of inspection and prevention than it 
does in more moderate environments. In such 
places periods of neglect to which no collection 
is absolutely immune can have extremely serious 
consequences, consequences which might well 
be escaped in a dry and temperate location. 
Other factors than climate must be taken into 
account: the risk of fire, earthquake and eruption 
must be considered, as well as that arising from 
war or civil disturbance. Recent examples of 
destruction or major damage show that none of 
these risks can safely be ignored. A disturbingly 
large proportion of major biological collections 
are located in the central parts of capital or indus- 
trial cities. How many of them could be evac- 
uated to safety in the event of a major catas- 
trophe such as a fire or the sudden cutbreak of 
modern war? Many of these risks could be 
minimized by suitable geographic location. 

The considerations that apply to the location 
of ordinary collections apply with redoubled 
force to the location of type specimens. It goes 
without saying that types ought to be kept in the 
safest possible location consistent with conve- 
nience of use. The two primary considerations, 
safety and convenience, are unfortunately to some 
extent opposed. This is particularly so in the 
problem of whether or not types shall be loaned. 
On the one hand a type is a unique standard, 
though not necessarily an irreplaceable one, now 
that the neotype is a recognized category, and 
there is a natural reluctance to expose it to the 
risks of shipment. On the other hand no location, 
however carefully chosen, can be convenient for 
all the workers likely to be interested in a given 
type, or even for a majority of them. As already 
noted, travel even when a possible solution is 
not always a complete one. There is little doubt 
that the inaccessibility of types is one of the 
major obstacles to taxonomic progress to-day, 
and the obvious answer is that the rigid immo- 
bilization of types as an invariable policy is 

73 



PROCEEDINGS OF THE NINTH PACIFIC SCIENCE CONGRESS 



wrong. No one would advocate the reckless 
shipping of types hither and thither on the 
slightest pretext and regardless of caution. On 
the contrary, every sensible person would want 
to minimize their movement. However, this is 
a very different thing from keeping them from 
moving at all. The loan of types to responsible 
individuals in deserving cases and with due atten- 
tion to safety in transit is in my opinion a very 
desirable thing; to oppose it is to take a ritualistic 
view of an essentially practical problem. What 
constitutes safety in transit is a debatable matter, 
almost as hard to define as what constitutes safe 
preservation in a museum. Possibly a system of 
personal carriage of types by entomologists 
known to be travelling in the desired direction 
could be established as a regular custom. 

The third of the major problems mentioned 
above, the availability of funds for work of world- 
wide or international scope, has become acute in 
recent years with the decline of private fortunes 
and endowments and the increasing importance 
of government support. Even some large private 
institutions have, in the face of shrinking funds, 
tended to confine their interests to limited geo- 
graphic areas, and this has almost been the rule 
with government museums. Counteracting this 
tendency are two favourable factors the activi- 
ties of the major research foundations, several 
of which have supported broad taxonomic work, 
and the increased realization of government 



departments that fundamental studies must 
receive their fair share of attention if more im- 
mediately applicable projects are to prosper. 
It may be hoped that these good tendencies will 
prevail, and that taxonomy will not lapse into an 
ineffective provincialism. 

DISCUSSION 

Dr. Mead wondered whether in view of the 
concept of species as a population and might 
eventually come to depend more on type localities 
rather than type species, and merely go to the 
locality and obtain samples of the population 
under consideration. 

Dr. Munroe pointed out that populations 
change, hence such a plan is unfeasible. Further, 
several closely related populations in one area 
would make it impossible to be certain one was 
sampling the right population. 

Dr. Cowan cited the extirpation of one species 
of wolves in Canada and their replacement by 
another species, a situation which would certainly 
negate Dr. Mead's proposition. Further, "ex- 
plosive populations" occurring at the time either 
of citing a type locality or at time of subsequent 
collection would add to the misrepresentation of 
such a sampling. 

Dr. Brongersma predicted that systematists 
would have to continue to inspect type collections 
and tolerate all the inconveniences entailed. 



74 



VOLUME 19 



ZOOLOGY 



COMPARATIVE RESEARCH OF BIOLOGY OF THE LITTORAL IN 

THE FAR EASTERN SEAS 

EUPRAXIE GURJANOVA 

The Zoological Institute, Academy of Sciences of the USSR, and the Leningrad University, Leningrad, U.S.S.R. 



A comparative research of biology of the 
sea-shore from the Barents sea to the Siberian 
seas in the Arctic and from the Berings Strait to 
the Korean peninsula in the Far-Eastern seas as 
well as in the Black sea and in the eastern part of 
the Baltic sea has been carried out during last 
30 years by the Soviet scientists. Last summer the 
area of these explorations was extended further 
to the South in the Yellow sea by the joint expe- 
dition of the Zoological Institute of the USSR 
and the Institute of Marine Biology of the 
Academia Sinica (Tsing Tao). All that enables 
us to formulate some general principles of the 
researches within the limits of the intertidal 
zone and to make some bionomic and biogeo- 
graphical conclusions. Our researches were 
based on the following basic ideas. 

1. Within sea-shore there are two zones 

situated above the lowest level of sea- 
Supralittoral and Littoral. Both are the 
independent zones of the ocean as they 
possess special conditions of life and a 
specific composition of fauna and flora; 
both of them greatly differ from other 
vertical subdivisions of sea or zones. 

2. The limits of Supralittoral are determined 

by the highest level of flood (lower limit) 
and by the bound of penetration of splash 
of waves (upper limit). There are land- 
conditions of life, but the irregular wetting 
of shore with sea-water creates some spe- 
cific biotops where both land (some plants, 
Insectes, Myriapoda, Mollusca, Arach- 
noiden) and marine organisms (algae, 
Crustacea, Mollusca and even fishes) 
find some favorable habitation. 

3. The limits of Littoral are determined by the 

maximum of theoretically possible level 
of high waters (upper limit) and by the 
level of maximum low waters or zero of 
depth used on the Soviet sea maps (lower 
limit). The daily regular uncovering 
creates here very specific amphibiotic 
conditions of life. 

4. The life of Littoral is subordinate to the 

rhythm of tides. All the factors of 
surroundings (t, salinity, light etc.) 



and especially the regular interchange of 
water-and air-conditions have diurnal 
fluctuations which depend on daily fluc- 
tuations of sea-level. Natural biological 
phenomena within this zone must be 
subordinate to this rhythm too (the time 
of spawning, the vertical migrations in 
soft ground of some verms and Bivalvia, 
hunting and nutrition of animals and the 
intensity of photosynthesis of algae and 
sea-plants etc.). 

5. The periodicity of all these changes depends 

on the type of tides which is characteristic 
of each region of sea-shore. 

6. Within littoral zone we can observe a regular 

change of life conditions in vertical direc- 
tion from the upper limit down to the 
lower one. Correspondingly we can 
see a clear vertical stratification of species 
and communities, each of them has its 
own place located at a definite level above 
zero depth and ordinarily forms some kind 
of belts (in conditions of arctic and boreal 
climatic zones) or mosaic (in conditions 
of south-boreal and subtropic zones). 
As our experiments show the vertical stratifica- 
tion of the littoral species depends on their 
capacity to bear fading and large rising heating 
or falling (freezing) of temperature. 

7. Zones and their upper and lower limits at 

each sea-shore area remain constant. 
As it is shown by K. Derjugin, 1928, zones 
and their vertical subdivisions do not 
change their places relative to zero depth. 
On the contrary, species and communities 
move within their zones up or down under 
the influence of changing of some defi- 
nite factors of surroundings, and even can 
move from one zone to another. 

8. If specific composition of fauna and flora 

is determined by some geographical, and 
historical factors (climate, paleogeography 
and origin and history of formation of 
fauna and flora of the region), the allot- 
ment of species and communities depends 
upon the present ecological conditions 
within the region. 

75 



PROCEEDINGS OF THE NINTH PACIFIC SCIENCE CONGRESS 



9. At first changes of surrounding conditions 
lead to change in vertical distribution 
of littoral species and communities but 
the specific composition of fauna and 
flora remains the same. We can observe 
on a sea-shore with normal salinity 
(33-35/oo) and calm water a normal 
stratification of communities which is 
typical for every geographical region. 
The whole system of communities rises 
up at exposed coasts and descends lower 
in brakish waters without breaking the 
order of their vertical zonation; rapid 
streams mixed communities together and 
their sharp stratification fades away. 
Thus the stratification of species and communi- 
ties is more sensible than their specific composi- 
tion and it indicates best of all the changing of 
conditions in comparison with the mean standard. 
In this way to be able to notice these kinds of 
bionomic change we must have some constant 
coordinates for comparison. Thus, the principle 
of vertical subdivision of intertidal zone which we 
consider to be a basic one has the most important 
significance in cognition of the regularities of 
littoral life. 

There are two kinds of subdivision of littoral 
zone into subzones, horizons, stories etc. Some 
authors use Vaillant's principle, which was 
applied by him to the North Atlantic coasts 



characterised by regular semidiurnal tides (Vail- 
lant, 1891). According to Vaillant, the limits of 
each of his three horizons are connected by 
definite sea-levels (Table I). That system was 
successfully applied to the Littoral of the 
Murman coast, White sea and Spitzbergen by 
Herzenstein, 1885, Knipowitsch, 1891, 1906 and 
Birula, 1894, 1896, 1898, 1906 and to the different 
areas of the Russian northern and far-eastern 
seas by Soviet authors (Gurjanova, 1935-1949; 
Gurjanova, Zachs, Ushakov, 1925-1930; Gur- 
janova, Ushakov, 1925-1930; Ushakov, 1949, 
1951; Kussakin, 1956 etc.). Other scientists use 
Stephenson's biological principle (T.A. Stephen- 
son and A. Stephensen, 1949) and subdivide the 
Littoral into subzones according to the distribu- 
tion of species. 

They do not take into consideration that a very 
close connection exists between vertical limits of 
the distribution of species and tidal sea-levels. 
The latter principle was subjected to a just critic- 
ism. To our mind this principle cannot be 
used in comparative bionomic study of intertidal 
zone without the help of the Vaillant's system 
of horizons, the limits of which are quite 
impersonal and exact. Besides, these limits are 
at the same time the critical levels of the major 
part of the littoral species; it is only not. quite 
clear for us whether the mean sea-levels during 
the different phases of tides or the highest and 



i 
1 



'a 
S 



Table I 

Regular Semidiurnal Tides 
(Barents sea) 

The highest level of High-waters of Spring-tides. 



H 



'- 

_ 



Exposed to air during Neap-tides. 

Covered with water twice per day during Spring-tides. 

Mean level of High-waters of Neap-tides. 



Covered with water and exposed to air twice per day, every day during Neap and 
Spring-tides. 

Mean level of Low-waters of Neap-tides. 



Covered with water during Neap-tides. 
Exposed to air twice per day during Spring-tides. 

The lowest level of Low-waters of Spring-tides. (Zero depth). 



76 



VOLUME 19 



ZOOLOGY 



the lowest ones coincide with the critical levels 
of littoral animals and plants the nearest. 

Researches carried out by the Soviet scientists 
show that the vertical distribution or stratification 
of littoral species and communities does not 
depend on the angle of bottom slope; the latter 
determines only the degree of development of 
the communities (Nordgaard's rule) and belts of 
species became wider or narrower with changing 
of this angle. 

The influence of amplitude of tidal fluctuations 
of sea-level is of the same kind: it determines only 
the space occupied by each of species or communi- 
ties but does not change their zonation. Only 
in one case the vertical distribution of species and 
communities does not depend on the tidal fluctua- 
tions of sea-level it is observed when the 
amplitude of these fluctuations (the range of tide) 
is smaller than changes of sea-level caused by 
winds. These conditions we can find in the 
Black, Azov and Baltic seas and in the Peter the 
Great Gulf (Japan sea). In all these cases the 
Soviet scientists use a new term "Pseudolittoral" 
zone (Mokijevsky, 1956). 

The comparative research of sea-shore of the 
north-western part of Pacific is especially inter- 
esting for there we can observe different types and 
different ranges of tides from 0.5 m to 13 m in 
different areas; it is especially interesting too 
for the coast-line passes through all four climatic 



zones of the northern hemisphere arctic, boreal 
subtropic and tropic ones without interruption 
and a permanent free exchange of fauna and 
flora can take place along the coast of Asia. 

As shown by our researches the Vaillant's 
principle of subdividing the intertidal zone can 
be applied not only to the sea-shore with regular 
semidiurnal tides, but to the places with other 
types of tides, i.e. with regular (Hon-Daw, 
Southern Chinese sea) and irregular diurnal 
(Petropavlovsk-Kamschatka, Kommander is- 
lands) and irregular semidiurnal tides as well 
(Soviet Harbour Japanese sea, Nagaeva bay, 
Taujsky bay Okhotsk sea). In all these three 
latter cases there are three horizons similar to 
those established by Vaillant. For each of them 
there are limits corresponding to mean levels 
of tropical and equidiurnal tides in places with 
regular and irregular diurnal tides as well as to 
mean levels of spring-and neap-waters in 
places with irregular semidiurnal tides. In cases 
of irregular tides there exist some additional 
limits, which divide horizons into stories (Tables 
II-IV); some special cases of irregular diurnal 
tides and of "shallow- water" tides are shown in 
Tables V and VI. 

The most complex cases of rhythm of life are 
observed within the places with irregular semidi- 
urnal tides, because the latter can be of three 
different kinds: 



Table II 

Regular Diurnal Tides 
The highest level of High-waters of Tropic-tides. 



H 



- =2.5. 



m 2 





o 


Exposed to air during Equidiurnal tides. 





N 


Covered with water once per day during Tropic-tides. 


o 


*""* ft* 




N 

< 





Mean level of High-waters of Equidiurnal-tides. 


LITTOR 


=1 


Exposed to air and covered with water once per day 
during both Equidiurnal and Tropic-tides. 


u- 
O 





Mean level of Low-waters of Equidiurnal-tides. 


2 






O 


2 


Covered with water during Equidiurnal tides. 


2 


HH N 


Exposed to air once per day during Tropic-tides. 


o 


NH p3 




DC 


s 


The lowest level of Low-waters of Tropic-tides. (Zero depth). 



77 



PROCEEDINGS OF THE NINTH PACIFIC SCIENCE CONGRESS 



Table III 
Irregular Semidiurnal Tides _ 

The highest level of High-waters of Spring-tides. 



H 



TH.2 



1 = 0.5, but 2.0. 



1 



8 

on 
Z 











O 

ffi 



i 







Exposed to air during whole period of Neap-tides. 

Covered with water once or twice per day during Spring-tides. 

Mean level of high High-waters of Neap-tides. 



Exposed to air and covered with water every day once or twice per day during both 
Spring and Neap-tides. 

Mean level of low Low-waters of Neap-tides. 



Covered with water during Neap-tides. 

Exposed to air once or twice per day during Spring-tides. 

The lowest level of low Low-waters of Spring-tides (Zero depth). 



o 

35 



Table IV 
Irregular Diurnal Tides 

The highest level of High-waters of Tropic-tides. 



Exposed to air during Equidiurnal tides. 

Covered with water once per day during Tropic tides. 

Mean level of High-waters of Equidiurnal-tides. 



H 



- - 1 - =2.0, but 4.0. 
m 2 



1 







g 
O 



Exposed to air and covered with water twice per day during 
Equidiurnal tides and once per day during Tropic-tides. 

Mean level of Low-waters of Equidiurnal-tides. 



Covered with water during Equidiurnal tides. 
Exposed to air once per day during Tropic-tides. 

The lowest level of Low-waters of Tropic-tides (Zero depth). 



78 



VOLUME 19 



ZOOLOGY 



1. The diurnal inequality is observed between 

adjoining (neighbouring) both high- 
and low-waters (Gongcong, Singapore, 
San Francisco, Freaser River etc.). 

2. The diurnal inequality takes place between 

adjoining highwaters only, but the neigh- 
bouring low-water have almost the same 
height (Soviet Harbour Japan sea, Shan- 
haj, Honolulu etc.). 

3. The diurnal inequality is characteristic 

only for adjoining low-waters, but be- 



tween neighbouring high-waters there is 
no difference (Nagaeva bay, Okhotsk 
sea etc.). 

In the first case the semidiurnal rhythm there 
is only within the horizon of Littoral; both first 
and third horizons have a diurnal rhythm. Water 
covers the first horizon once per day during the 
whole lunar-month; the lower limit of this horizon 
is the mean spring low-high-waters level; here 
there are two stories upper one which is covered 
with water once per day only during spring-tides, 



Table V 

A Specific Case of Irregular Diurnal Tides 
(Kommander Islands)* 

The highest level of High-water of Tropic-tides. 



H, 







m.2 



HORIZONS OF LITTORAL ZONE j 


I HORIZON 


Exposed to air during equidiurnal tides; covered with water once per day during 
tropic tides. 

Mean level of high High-waters of Equidiurnal-tides. 


II HORIZON 


STORIES OF 
II HORIZON 


1 STORY 


Covered by water and exposed to air once per day during tropic tides 
and twice per day during Equidiurnal tides. 

Mean level of high Low-waters of Equidiurnal-tides. 


2 STORY 


Covered by water and exposed to air once per day 
during the whole lunar month. 

Mean level of low Low-waters of Equidiurnal-tides. 


III HORIZON 


STORIES OF 
HI HORIZON 

. 


1 STORY 


Exposed to air once per day during tropic-tides. 
Covered with water during Equidiurnal-tides. 

Mean level of low Low-water of Tropic-tides. 


1 

<s 


Covered with water during Equidiurnal and ordinary Tropic-tides; 
exposed to air once per day during "large" tropic-tides in Spring time. 

The lowest level of Low-waters of Tropic tides in Spring-time. 



* Tides within the Kommander islands are of the same type as within the eastern coast of Kamtschatka (Petropavlovsk), i.e. irregular diurnal 
ones; but they have some specific features: 

1. A large diurnal inequality of adjoining low waters of semidiurnal equidiurnal tides; 

2. A considerable difference of heights between high waters of tropic and equidiurnal tides; 

3. The existence of some "large" low waters, which are very rare and take place almost exclusively in Spring time (March-April). 

79 



PROCEEDINGS OF THE NINTH PACIFIC SCIENCE CONGRESS 



and the lower one which is covered with water 
once a day during both spring -and neap-tides. 
The second horizon has a semidiurnal rhythm, 
but is clearly divided into three stories upper 
one has a semidiurnal rhythm only during spring- 
tides as both adjoining high-waters cover it, 



but during neap-tides period it is covered once 
per day by high-waters only. Second or middle 
story has a semidiurnal exchange of air and water 
conditions every day; the lower story is analogous 
to the upper one as it has a diurnal rhythm during 
neap-tides and a semidiurnal rhythm during the 



Table VI 

"Shallow- Water" Tides Within the coasts of the 

Shandunsky Peninsula, Yellow Sea 

Regular semidiurnal tides. 

The highest level of High-waters of Spring-tides* 



Hr 



= 0.38 



I 

I-J 

U< 
O 

i 



z 
o 



i 





s 



Exposed to air during Neap-tides. 


Covered with water once per day during Spring-tides. 


Mean level of low High- waters of Spring-tides high High- 


waters of Neap-tides. 






Covered with water once per day during Neap-tides and twice per day 





1 


during Spring-tides. 


o 




Mean level of low High-water of Neap-tides. 


N 






2 










8 




Covered by water and exposed to air twice per day during whole lunar 


HH 


2 


month. 


8 




Mean level of high Low-water of Neap-tides. 


P-l 

5 




Exposed to air once per day during Neap-tides and twice per day 


8 


3 


during Spring-tides. 


C/5 










Mean level of low Low-waters of Neap-tides. 






Covered with water during Neap-tides; 


b 


1 


exposed to air twice per day during Spring-tides. 







Mean level of high Low-waters of Spring-tides. 


W3 

25 










gs 


2 


Covered with water during Neap-tides and ordinary Spring-tides; 
exposed to air rarely during "large" Low-water of Spring-tides. 






The lowest level of low Low-water of Spring-tides. 



Hera as well as within the Kommander islands some very "Large", but rare ebbs occur generally in winter. Tides have the semidiurnal 
rhythm, but there is a considerable diurnal inequality of adjoining low waters; the heights of adjoining high waters are epual; a coinciding of 
low high water of Spring-tides and high High-waters of Neap-tides takes place here. 

80 



VOLUME 19 



ZOOLOGY 



Table VII. 

Vertical Distribution of Animals within the Muddy Beach Tsan-kow near Tsing Tao (Yellow Sea, 
Southern Coast of Shandunsky Peninsula). Subtropic Geographical Zone. 

(After E. Gurjanova, Y. Liu, O.Scarlato, T. Tsi and P. Ushakov, 1957) 



4.5m 


SUPRALIT- I 
TORAL ZONE]] 


No animals or plants 
4.5 m 


3.6-m 


UJ 

Z 

o 

N 

J 
< 
& 

H 

H 

* 
J 


I HORIZON 


2 i 
STORY STORY 


Helice tridens 
(many specimens) 


Sesarma sp. 
(under gravel and small stones) 
4.1 m 


Scopimera globosa (few specimens) 
3.6 m 


1.6m 


Z 



2 

i 

1 
1 

NH 
>* 


1 STORY 


Scopimera globosa 
(many specimens) 


Perenereis nuntia v.brevicirrus 
Audouinia sp. 
Lingula anatina juv. (few specimens) 
2.9 m 


2 STORY 


Macrophthalmus 
japonicus and 
Lingula anatina 


Perenereis sp.; Audouinia sp.; Glyccra 
sp. ; Platinereis sp.; Alpheus sp. many; 
Solen gouldi many; Bullacta exarata; 
Hemigrapsus penicillatus many; 
Scopimera globosa (few); Diapatra 
neapolitana; Lumbriconereis sp.; Upo- 
gebia major (few specimens and very 
deep in mud). 
2.0 m 


3 STORY 


Upogebia major 
(a great many) and 
Gavernularia sp. 


Mactra quadrangularis; Dosinia sp. ; 
Dosinia japonica; Venerupis philippina- 
rum; Solen gouldi; Vivariegatas; Hi- 
ma sp.; Anatina peckohiliensis; Thalas- 
sema sp. ; Morphysa sp. ; Diopatra nea- 
politana; Lumbriconereis sp. ; Amphi- 
ura valida; Alpheus No.2 and others. 
1.6 m 


1 STORY 


Macrophthalmus 
dilatatus 
(a great many) 


Philine kinglipini; Alectrion variceferus; 
Dosinia japonica; Solen gouldi; Mactra 
sp.; M. quadrangularis; Amphiura vali- 
da; Venerupis variegatus; Armandia sp. 
Pota milla sp. ; Balanoglossus ; Callianas- 
sa 2 species; Pilyra carinata etc. 
0.5 m 





cs 


Upogebia wusienwe- 
ni and Lingula sp. 
No. 2 


Branchiostoma belcheri var. tsingtao- 
ensis ; Matata planipes; Oryphia macu- 
lata and some sublittoral species. 

(Zero depth) m 



(datum) 



81 



PROCEEDINGS OF THE NINTH PACIFIC SCIENCE CONGRESS 



Table Vlll. 
Vertical Distribution of Species and Communities within the Rocky Beach near Nikolskoje (Berings Isle, Kommander Islands). 



5 m 



Irregular diurnal tides. Temperate geographic zone 
(After E. Gurjanova, 1930-1931) 



Limit of splash 5 m 



4 m 
3.26 


SUPRALITTORAL ZONE 1 


I HORIZON 1 


Plants and animals. Lathyrus maritimus; larvae of Coleoptera and Diptera ; Myriapoda ; Machilis sp. ; 
Mertensia maritima; Ligusticumscoticum; Turbonilla sp.; Helix sp.; Arachnoidea; 
Allorchestes wladimiri; Orchestia trinitatis; 
SAND AND GRAVEL 
limit of surf-washing 4 m 


II HORIZON 


Only animals. Orchestia trinitatis; Allorchestes wladimiri; Anisogammarus locustoides; Echinogammarus 
ochotcnsis; De tone llapapillicorn is; Halobcsiumorientale; Staphilinidae; Oligochaeta; Lit tori na sithana(few). 

SAND AND STONES 
3.26 m 


3 m 


w 
Z 

O 
N 

-l 
< 
t* 
O 
H 
H 

_J 


I HORIZON 


STORY 


Littorina sithana 
(many) 


Green algae, Uropora and Prasiola in Spring. 
Bangia fuscopurpurea + 2 species of Gleiopeltis in Summer. 
3.0 m 


2.46 


2 STORY 


Littorina sithana 

+ 
Acmaea No. 1 


Belt of Diatomacea (Melosira sp.) in Spring. 
In Summer algae are absent. 

2.46 m 


2 m 


II HORIZON 


I STORY 


Acmaea No. I. Littorina 
sithana Echinogammarus sp. 
Gammarus sp. 


Belt of Porphyra and Dip lode rma in Spring. 
Belt of Gloiopeltis furcata in Summer. 
Fucus evanesce ns whole year. 
2.00 m 


1.20 


2 STORY 


Fucus cvanesccns and 
Mytilus edulis 


L. sithana ; Acmaea No. 2; several species of Gammaridae ; Lineus sp.; small Polychaeta; 
Acmaea No. 1 ; Ischnochiton rubcr; Pagumshirsutiusculus; Janiropsis kincaidi. 


Odonthalia floccosa 
coniosa 


Phiscosoma japonica; Thais lima; Acmaea No. 2; Acmaea 
No. 3; Pagurus hirsutiusculus; P. middendorfi ; Cucumaria 
vegac juv. very many in Spring. 


Fucus inflatus and 
Rhodymenia palmata 


Alaria sp. (rare); Idothea allutica; Chiton 2 species; Pagurus 
hirsutiusculus; P. middendorfi; P. gilli; Hapalogaster grebnitz- 
kii; Dermaturus brandti; very rich fauna of Gammarids and 
Polychaeta. 
1.20 m 


1 m 


III HORIZON 


2 STORY: I STORY 


hf&jjiii 

3 


Very rich fauna of Crustacea, vermes and Mollusca; Pagurus 
middendorfii; P. galli; Hapologaster grebnitzkii; Dermaturus 
mandti: Paralithodes brevipes juv.; Cheiragonus cheiragonus; 
Leptasterias 2 species. 
1.00 m 


m 


SEMIBALANUS CARIOS 

SPIRORBIS SEMIDENTATUS; 
LITHOTHAMNIUM SP. 


Laminaria 
dentigera 
Amphiroa 


vicutccu 

Schizobran 
chus insig- 
nis 


Pagurus gilli ; P. undosus; Hapalogaster Amphineura 5 species; 
Leptasterias 2 species; and Dermaturus; Paralibrotus brevipes 
juv.; Strongylocentrotus 2 species; Cheiragonus; Oregonia 
gracilis; very rich fauna of Polychaeta, Amphipoda, Mollusca, 
Nemertini. 
0.60 m 


Thalassiophyllum Rich fauna of sessile animals; Leptasterias 2 species; Henricia 
clathrum + Spongia, several species; Strongylocentrotus 2 species; Schizoplax brand- 
Synascidiae, Bryozoa ti; Cryptochiton stellcri and other species of Amphineura; 
on the thai 1 us. Monia macroschisma; Hapalogaster, Dermaturus, Paralithodes 
brevipes, Oregon ia gracilis, Pugettia quadridens; several species 
of fishes; the richest fauna of Mollusca, Polychaeta, Ampra'poda 
and Isopoda. 
(Zero depth) 



82 



period of spring-tides. The upper limit of the 
third horizon (and the lower limit of the second 
one) is the mean high low-waters level of neap- 
tides. 

In the second case the first horizon of Littoral 
is very short in vertical direction because its lower 
limit is the mean high-waters level of spring tides; 
this horizon is covered with water only during 
spring-tides and has a semidiurnal rhythm as 
the adjoining high-waters have almost the same 
height. The second (middle) horizon has a semi- 
diurnal rhythm during the whole lunar-month as 
its lower limit is the mean high low-water level 
of spring-tides. This horizon is divided into 
two stories the upper one has always a semidi- 
urnal rhythm; the lower story during neap-tides 
has a diurnal rhythm but a semidiurnal one is 
observed only during spring-tides. The third 
horizon has always a diurnal rhythm and is divided 
into two stories the upper one exposed to air 
every day once a day, the lower one exposed 
to air once a day only during spring-tides. 

In the third case when the diurnal inequality 
takes place between adjoining high-waters only, 
the first horizon has always a diurnal rhythm 
as the lower limit of it is the mean low high-water 
level of spring-tides. This horizon has two 
stories the first one is covered with water only 
once a day during spring-tides, the second one 
is covered with water once a day every day during 
lunar month. 

The second (middle) horizon has a semidiurnal 
rhythm and is divided into two stories too the 
first one has a semidiurnal rhythm during spring- 
tides only, the second one has such a rhythm 
during the whole lunar month, as the lower limit 
of the horizon (= upper limit of the third horizon) 
is the mean low water level of neap-tides. The 
third horizon is exposed to air only during 
spring-tides and as both adjoining low waters 
have no difference in their heights, this horizon 
has a semidiurnal rhythm. 

Some specific rhythm of life is characteristic 
in conditions of "shallow-water" tides. An 
example of it is shown in Table VI. Within 
Shandunsky peninsula tides are regular semidiur- 
nal (see the formula of them); but very small 
depth of Yellow sea caused out some special 
deformation of tides: as result the first horizon 
has a diurnal rhythm, the second (middle) horizon 
is divided into three stories and each of them has 
its own rhythm of life; the thrid (lower) horizon 
is divided into two stories and each of them 
has its own rhythm too (Table VI). 



VOLUMB 19 _____ ZOOLOGY 

The difference of tides rhythm within different 
parts of amphibiotic littoral zone show the 
necessity of subdividing this zone into horizons 
and stories according to Vaillant's principle; 
without it we can not catch regularities of littoral 
life and will not understand the causal dependen- 
cy between biological phenomena and their sur- 
roundings. 

We have many practical Tables illustrating the 
vertical distribution of communities and their 
specific composition as well as absolute position 
of their limits above datum (zero of depth) 
(Gurjanova E.F., 1924-1949; Gurjanova E., 
Ushakov P., 1928-1925; Gurjanova E., Zachs 
J., Ushakov P., 1925-1930 etc.); in these Tables 
the limits of horizons and their stories are shown 
too. As examples I would like to show only two 
such Tables (Tables VII and VIII); they both 
reflect the natural distribution of species within 
the place with mean normal conditions. Having 
such Tables made by researchers for every place 
visited by them it is possible to compare directly 
littoral zones of different seas and climatic zones 
and make some bionomic and biogcographical 
conclusions. 

If zonation proposed by Stephenson can be 
applied to rocky beaches only, the zonation based 
on Vaillant's principle can be used for different 
kinds of beaches rocky, stony, sandy, muddy- 
beach etc. 

The most specific feature of the Far-Eastern 
seas in comparison with Atlantic coasts is the 
existence of two datums (zeros of depth). This 
phenomenon depends on the monsoon climate 
and the periodical law of Tsusima current out-go. 
At the western coast of the Japan sea, for exam- 
ple, zero of depth in winter lies lower than in 
summer by 30-45 cm. 

Thus we have here an additional specific inter- 
mediate horizon between littoral and sublittoral 
zones covered with water during the whole 
summer and exposed to air during ebbs only in 
winter (from October to April), when the mean 
sea level is lower. In such a way within the lower 
part of Littoral a semiannual rhythm of life 
exists here besides diurnal or semidiurnal one. 
Adaptations of sea-shore species to these specific 
conditions had stipulated the existence at the 
western coast of Japan sea of fauna and flora 
spreaded from the middle part of Littoral to the 
depth of 15 m, i.e. the most part of the sea- 
shore species here is adapted to conditions not 
only of intertidal zone but to conditions of sub- 
littoral too. 

83 



PROCEEDINGS OF THE NINTH PACIFIC SCIENCE CONGRESS 



When examining our materials we came across 
many general and specific bionomic regularities 
(see our articles). 

As the coastal line of the USSR is an enormous 
one we can observe and study some geographical 
regularities too. Thus, we may clearly see the 
practical illustration of the Dokuchaev Berg's 
law of the geographical zonation. On the other 
hand it is possible for us to define precisely the 
system of biogeographical regions and their 
subdivisions for the littoral zone. 

Gurjanova E., Zachs, J., Ushakov P., 1925 had 
shown that the limits of biogeographical regions 
and provinces of the Littoral of arctic seas do not 
coincide with the limits of biogeopgraphical 
subdivisions of the sumberged sublittoral zone of 
the Northern Polar Basin. Such a fact was 
known before only for sublittoral and abyssal 
zones: Schmardd, 1853; Ortmann, 1896; Sv. 
Ekman, 1935 (regarding the whole World ocean) 
had given the system of zoogeographical shelf 
for continental shelf and for abyssal bottom 
separately. 

Gurjanova, 1951, had shown the same fact for 
the. Northern Polar Basin. 

Kussakin, 1956, has given a biogeographical 
subdivision of the littoral zone of the Kurilo- 
Sacchalin area; we may see that the limits of his 
littoral provinces do not coincide also with our 
subdivisions (Gurjanova E., 1955) of the sublit- 
toral of this area quite exactly. Moreover, 
it seems to me that coincidence of limits of 
zoogeographical regions, provinces etc. within 
different vertical zones of seas can not be, that 
the phenomenon is quite natural and that it is a 
general law. By the study of some biogeograph- 
ical regularities it is necessary to regard each 
of marine vertical zones of ocean separately and 
the littoral zone, of course, too. 

REFERENCE 

Abrikosov G., Sokolova H., 1948, To research 
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(Russ.). 

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Birula A., 1894, Review of the work in the zoo- 
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84 



Birula A., 1896, Review of the work on the zoo- 
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Birula A., 1898, Review of the work on the 
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Duvanin A.J., 1948, Calculation of the charac- 
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Gerzenstein S.J., 1885, Materials on the fauna 
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Gislen Torsten., 1943, 1944, Physiographical and 
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Gurjanova E., 1935, Kommander islands and 
their sea-shore fauna and flora. Nature, 
11 (Russ.). 



VOLUME 19 



ZOOLOGY 



Gurjanova E., 1935, A short characteristic of 
Benthos within the region of the 
Sud-ze-che and Sjau-che (Japan sea). 

Gurjanova E., 1935, A short characteristic of 
Benthos within the region of the Sud- 
-ze-che and Sjau-che (Japan sea). News 
of the Far-Eastern Department of the 
Acad. Sc. USSR, v. 12. (Russ.). 

Gurjanova E., 1948, The White sea and its Fauna. 
Petrozavodsk, USSR. (Russ.). 

Gurjanova E., 1949, Regularities of the specific 
composition and distribution of Fauna 
and Flora within the western part of 
the White sea. Travaux de la Station 
marino-biologique de rUniversite Karlo- 
Finn. (Gridino), v. 1. (Russ.). 

Gurjanova E., 1949, Specific features of the 
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the University of Leningrad, 3. 

Gurjanova E., 1951, Gammaroidea of the seas of 
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Fauna of USSR, v. 41. (Russ.). 69-123 
+ Fig. 30. 

Gurjanova E., 1955, Zoogeographical subdivi- 
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v. 1. map 38 + text. (Russ.). 

Gurjanova E., Zachs J., Ushakov P., 1925, Das 
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Gurjanova E., Zachs J., Uschakov P., 1925, Ver- 
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Gurjanova E., Uschakov P., 1928, Zu der 
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Gurjanova E,, Liu J., Scarlato O., Tai T., 
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verticale des animaux. Congres Internal. 

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(Kurila islands). Trudi problemnich 

i tematicheskich sovestchanij. VI. 

Zoolog. Institute of the Acad. Set. of 

the USSR. (Russ.). 
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within the Littoral of the western coast 

of the Crimea. Trudi Instituta Oceano- 

logii, IV. (Russ.). 
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the estuary of Amur River. Comptes 

Rendus de VAcad. des Set. d'URSS, 

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Oceanologii, XII. (Russ.). 
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Ecology, v., 37, No. 2. 

85 



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